V10 rules select folder window doesn't work

folder selection window shows up, you can select folders, but can’t accept (or cancel) the window. Only the small x in the upper right cornet let’s you exit the window again. Selection is of course not stored then

you don’t get an errror message? when i try to replicate that i’m either allowed to do it or i get an error message. for rules i can select one folder only. and (that’s more a guess) origin and destiny shouldn’t be the same.
what action doesn’t give a error message?

now, miraculously, it works.
Selfhealing? Heisenbug??