Renoise’s internal shrik/expand functionality (here super F8 / super F9) has the same bug as described here in the pattern expand tool:https://forum.renoise.com/t/new-tool-2-8-3-0-flexible-pattern-resizer/30664
If a automation point is on the very last position of a pattern (so the same position as the first in the next pattern), this point will be erased while a pattern shrink.
The point doesn’t have to be exactly on the last line, all points between pre-last and last line will disappear.