Hey Steven, I found another bug. This time I went ahead and added it to the issues on github; it's #249.
The problem is with using the line point editor to edit automation points numerically; it seems that the position of the last point can't be edited.
Workaround is to add a bogus "last point", and delete that after editing the now next-to-last point in the line point editor. (Once again, I have a workaround, so don't consider this critical.)
I would also like to be able to add and delete points in the line point editor -- I didn't put that feature request in the bug because I didn't want to conflate issues.