I am trying to validate PRDs but the project checker window never shows
a thing. But validation itself seems to work since it does not let me
deploy PRDs whose validation fails.

How could I get bring the project checker window back alive?

Designer is version 4.0.2 and the destination IDM UA driver seems to be
of version 3 (version number in driver trace shows year 2010). But the
UA itself seems to be of version 4... this might be problematic too I

I am also missing activity icons but possibly that is due to older
version of UA driver in IDM.