Most probably there are other functions that could trigger this problem, but for me the most sure replication of the problem is this:
Put down a Line Trace by Channel block.
“Scroll” down so far that you can only see its bottom, like “Draw debug type”, or “Ignore self”.
Put down a Switch Has Authority block.
What you see: The LineTrace block disappears.
It reappears if you go up a bit, but not immediately.
Same happens if you delete the Switch has Authority block at the same view.
Thanks for your report. I have been able to reproduce this behavior, and have tested it and acknowledged that it happens with several nodes.
However, there has been a bug entered for a similar issue with the same root cause that the developers have decided not to fix at this time due to the fact that it does not affect functionality, and that they are currently focusing their efforts on high-priority crash and showstopper bugs.