Both India and Bhutan were Ok with China's presence in the northern part of the plateau, since China had been present there and was building roads long before 2017. The issue was China unilaterally attempted to extend the road to the south towards Mt. Gipmochi, near an area called Zampheri ridge, without consulting Bhutan. Construction of the road was stopped, and although China has been building roads elsewhere nearby in non-disputed areas, China still hasn't built any roads towards jampheri.
And its not like China would have accepted an agreement favorable to Bhutan. China was willing to offer it some less strategic land in the north in exchange for the Southern part of the Plateau, due to the strategic importance of Jampheri
Recently, China has even tried offering the Sakteng wildlife sanctuary in exchange for South Doklam, despite the fact that the area is already controlled by Bhutan. In addition, China claims that as its territory, even though it does not border China. Though it does border Arunachal's Tawang district.
So it's not like India simply interfered in bilateral Sino-Bhutanese negotiations.