I will make some assumptions first prior to answering, since otherwise the answer would be excessively long:
- By "which scholars", I am assuming you are referring to hadith scholars only.
- By "denied ahadith", I am assuming denied that there is a hadith of that level (not denying the concept itself).
- By "being mutawwatir", I am assuming that the definition is the most commonly accepted one of three trustworthy narration chains.
No hadith scholars denied (in the sense that they said it is wrong) the concept of tawātur at large, simply because the concept of hadith mutawātir does not come from scholars of hadith. This is why none of the major hadiths books uses the word mutawātir in their titles or in their content. They use sahīh (authentic) instead.
The origin of the word hadith mutawātir comes from the fundamentalists of jurisprudence (Arabic: الأصوليين, al-Usūliyyīn). This was added by jurisprudence scholars, according to Ibn al-Salāh in his Muqaddima (Arabic: مقدمة ابن الصلاح), to set different criteria for requirements of an act:
- Hadith mutawātir is obligatory without any further knowledge being required.
- Hadith ahād is obligatory when supported by knowledge.
Ibn al-Salāh classified hadith as either authentic or weak for the purpose of chain validation. Ibn Hajar al-Asqalani further explained in Nozhat al-Nadhar (Arabic: نزهة النظر) that the reason that there are no clear criteria for what is considered mutawātir among hadith scholars is that hadith scholars are only concerned with the authenticity of the chain of narration, not with the consequences of the interpretation of the hadith, or the frequency of narrations.
So this takes us to what a khabar is, what a hadith is, and what mutawātir is.
Hadith is what is narrated through or about the Prophet ﷺ as either his saying, his action, his concurrence, or his description (his appearance, his manners, or his history or sīrah).
Khabar includes hadith, according to a number of scholars, in addition to what was narrated by and attributed to others (e.g., companions, or the two generations that follow). This classification is arbitrary. Other scholars consider a narration through the Prophet ﷺ to be hadith, and a narration not through the Prophet ﷺ as khabar.
Lawāmi' al-Anwār (Arabic: لوامع الأنوار البهية) explains that the definition of tawātur is not agreed upon through a frequency of narration. Ibn Qadi al-Jabal said that tawātur is what equates to being sure that it was narrated through the Prophet ﷺ.
What is commonly accepted among most is that a hadith with more than three authentic narration chain is considered mutawātir. For the purpose of this answer, we will consider the most commonly-accepted definition of mutawātir, which is three narration chains, with one or more in the companions layer, and at least two narrators in each following layer, that qualify for being trustworthy, i.e., of integrity (Arabic: عدل) and sound memory (Arabic: تام الضبط), without irregularity (Arabic: من غير شذوذ) or flaw (Arabic: من غير علة). Some consider two chains to be enough to call a hadith mutawātir, while others would only accept ten or more. Hence, Ibn Hibbān's statement.
Ibn Hibbān is referring to khabar to include hadiths. His full statement shows that he was addressing a specific definition of tawātur that the majority of hadiths would not have (not per se the commonly-accepted definition):
وأما الأخبار فإنها كلها أخبار آحاد ; لأن ليس يوجد عن النبي ﷺ خبر من رواية عدلين، روى أحدهما عن عدلين وكل واحد منهما عن عدلين حتى ينتهي ذلك إلى النبي صلى الله عليه وسلم، فلما استحال هذا وبطل، ثبت أن الأخبار كلها أخبار آحاد، ومن رد قبوله فقد رد السنة كلها لعدم وجود السنن إلا من رواية الآحاد
— NOTE: My own translation, so treat with care:
As for al-Akhbār [news], all akhbār are ahād. This is because there is no khabar about the Prophet ﷺ that goes through two trustworthy person, each who has narrated through two trustworthy people, each through two trustworthy people all the way to Prophet ﷺ. Since this is impossible and is incorrect, it has been proven that all akhbār are ahād, and whoever rejects ahād [as authentic] is rejecting the Sunnah, for the Sunnah is comprised of ahād.
Note that this definition above requires two companions, four tabi'is, eight tabi'is al-tabi'i, and sixteen narrators to have at least narrated the hadith to satisfy the requirements of it being mutawātir. This goes to 32 additional narrators for a 5-level hadith, an additional 64 for a 6-level hadith, and an additional 128 for a 7-level hadith.
As for this particular concept of tawātur (two through two through two through two), this view was also shared by Abu-Bakr al-Hazimi (Arabic: أبو بكر محمد بن موسى الحازمي). It is about jurisprudence fundamentalists requiring a certain number of authenticated chains to consider a hadith mutawātir, and thus obligatory under all conditions. It is not to deny the concept of tawātur at large. Moreover, both scholars actually missed the hadith that you mentioned as being the only accepted as hadith mutawātir (Sahih al-Bukhāri 106), was narrated by more than 60 companions, and there other hadiths that has tens of narrators in the companion level.
It is true that several hadith scholars — under a specific context, based on a particular definition by jurisprudence fundamentalists — said that one or a few hadiths are mutawātir, but this was always in a specific context. Not all hadith scholars, however, are of the opinion that all conditions for a hadith mutawātir are always impossible to meet. In Al-Nokat 'ala Moqaddimat Ibn al-Salāĥ (Arabic: النكت على مقدمة ابن الصلاح), Vol. 1, 1st Ed., 1998, pp. 258-267, Al-Zarkashi extensively discusses this topic. Some scholars say about 10,000 hadiths meet one or more set of criteria defined for hadith mutawātir. He refers to several hadiths by al-Bukhāri and Muslim that were included in their Sahīhs, but without meeting certain definitions of mutawātir.
One final note on scholars that do not consider hadith to be khabar, all akhbār would by definition be ahād, as they would all come through only one in the layer of the companions.
In conclusion, hadith scholars do not typically use the term mutawātir; hence, no hadith scholar will either accept or reject a hadith based on this. Their definition is that once a narration chain is established, then the hadith is authentic and mandatory to follow. Jurisprudence scholars added the definition of tawātur in hadith, but did not establish an agreed-upon set of criteria. No scholar deny tawātur as a concept, but rather the applicability of certain strict requirements in specific definitions. No hadith scholar denies Ibn Qadi's statement that tawātur is what equates to being sure that it was narrated through the Prophet ﷺ.
