+++ This bug was initially created as a clone of Bug #421542 +++
[Frameworks/plasma git-master, so this is the redesigned window rules kcm.  qt-5.15.0_rc ]

[Split from above bug on request.]

When adding a new rule window role doesn't originally appear.  Not only is it not in the original matching list, but hitting add properties, it doesn't (originally) appear either -- tho the first slot under window matching is blank, and if you begin to type the first two letters of "role" (so "ro") in the search box, it does appear.  If you then close the add/select properties box and click add properties again (after searching for it the first time), it shows up in the position that was previously blank.