I'm probably doing something dumb, but:

I am invoking mystic to edit an ANS file thusly...

./mystic -ansi blah.asc

While editing I am trying to copy blocks of text from one line to another. I got as far as using ctrl-b to select a block (nifty, that), but when I try to paste it, I am using ctrl-u, which does not work. The menus seem to suggest
it does, but either I am doing something wrong or something's broken.

Based on long personal experience I am probably doing something wrong, and I
am hoping someone can tell me what. :)

--- Mystic BBS v1.12 A39 2018/04/21 (Linux/64)
* Origin: Retro Underground BBS | Seattle (21:4/141)