Forum categories won't show up, @LeonidS . Pls, see screenshots attached.

What I found so far is that the Discussion Categories block on Discussions Home page works, but seetings for that block look different than those for the Discussion Categories block from the add block list I used for displaying categories on my main site. The one showing has a field "Menu" with selection "Categories". The block not showing has other settings which can't be changed. See the attached screenshots.