It might be a bug, but I wanted to make sure someone else noticed that weight painting is not respecting the mesh deformation as shown in the gif.
Well, it’s 2.8, so no doubt it’s a bug. If you close Blender and reopen the file you might be lucky and it will work again. Otherwise, it’ll be fixed at some point.
Yeah… no luck reopening the file… guess I’ll have to wait. Until then, I might just toggle the armature modifier off when painting weights or manually assigning weights to the vertices.
Blender 2.8 is already in Beta. This means that the bugtracker is open to all bugs, not only crash reports. You should look if somebody already reported this bug and if not you should report it yourself.
The weight painting making the assumption of the vertices being in their original position (before deformation) is a regression and should be reported.
As mentioned, the bug tracker is open for all reports now.
Ok, thanks for the heads up, guys! It looks like the issue has been fixed in the latest build, and was already reported here https://developer.blender.org/T58685.