Using EEVEE (as well as some other actions like saving the file or
tweaking mesh parameters) can cause a PBVH rebuild. The different sculpt
tools can store PBVH nodes or other related data in their caches, so
this data becomes invalid if the PBVH rebuilds during evaluation. This
ensures that the PBVH does not rebuild while the cache of Expand is
being used, like it already happens for brushes and filters.