**System Information**
Operating system: Windows-10-10.0.1709 64 Bits
Graphics card: GeForce GTX 1050 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 416.34
**Blender Version**
Broken: version: 2.81 (sub 10), branch: master, commit date: 2019-09-10 15:51, hash: `rB01a3a9c8181d`
**Short description of error**
Grab Active Vertex and Dynamic Mesh Preview are not working, You get locked and the UI flickers.
You have to kill Blender from the Task Manager and sometimes simply Crashes.
**Exact steps for others to reproduce the error**
Have an Object with Subdivison Modifier->Sculpt Mode-> Grab Brush->Enable Grab Active Vertex(Brush Settings).
Demo of the Bug:
{F7731861}
Blend File:
{F7731812}