I can't remember when it started, but I've had this issue for over a year. Every time the game is patched I give it a go, but it's still the same.
The issue is that the curses blinks/disappears when moving it in paused mode. When the game is running it's completely smooth.
I've seen a few people mentioning the bug, but I don't think it's been recorded so that people can see what's going on. So I recorded it, and you can see it in action below.https://streamable.com/z3gqn
It's very disturbing, and sadly I end up turning away from the game every time because I need to build while paused.
There exists a bug report
on it, but sadly it has not received any attention for almost 4 years.