Undo/Redo in 2018.1 often gets blocked (by workspace.xml changes?)

I often end up with a blocked undo history because of changes made to other files, and suspiciously the workspace.xml file always ends up in there, with other source files that I'm sure I haven't touched in the history chain at the point I'm requesting an UNDO. I suspect the workspace state change is what's blocking and this smells like a bug.

I'm using IntelliJ IDEA Ultimate.

Is anyone else experiencing this? I couldn't find any open issues yet, but wanted to check with the community before pushing a new one.

Cheers