System Information
Operating system: Linux-3.10.0-957.10.1.el7.x86_64-x86_64-with-centos-7.6.1810-Core 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 418.56

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-07-08 14:18, hash: rBa4bc6aca0ef9
Worked: 2.79 and some previous 2.8s

Short description of error
If you alter the mesh in multires mode and then add a new subdiv, mesh gets disturbed. It's basically brakes the whole sculpting in Blender.

Exact steps for others to reproduce the error

1. Create any object with decent amount of polys
2. Go in sculpt mode
3. Add multires
4. Add one subdiv
5. Use the grab brush to alter the mesh
6. Add another subdiv level

PS: multiple 'apply base' button hitting tears the mesh apart.