win10 64, nvidia 1060
Short description of error
When you disable "Lock object mode" in the Edit menu, and sculpt on one ojbect, if you select a second object, the sculpted changes will "disappear" from the first. The changes are still there, you just have to select the first object and you can see them, but selecting back and forth between the two objects will make the changes appear and disappear. And in order for this to not happen, you have to get out of Sculpt mode, but it will happen once you sculpt again.
Exact steps for others to reproduce the error
Using the attached blendfile, make sure "Lock object mode" is disabled in the Edit menu. The red monkey is already selected and in sculpt mode. Sculpt visible changes on the red monkey, select the white monkey (right click select presumably) and see the changes dissapear, select the red monkey again and see the changes come back.