This is an issue revealed by the recent optimization in 4d3bfb3f41 to have
CPU and GPU subdivision topology both cached.
BKE_subsurf_modifier_subdiv_descriptor_ensure is what (re)creates the
topology refiner when needed. Invalidating the topology refiner on changes
must be done before it, otherwise we end up with an incomplete Subdiv that
either does not draw or draws incorrectly.
Pull Request: blender/blender#105844