If I want to update my element’s translationY to be 100% - 30px for example, I can do that by going under Transform → Move and using a calc() expression. It works, but once I exit, the input for that value disappears:
This also means that the latter half of the expression is cut off in the sidebar:
So if you want to see what you set it to, you can only see the first half. If you want to edit it, you have to completely remove the translation transform and re-add it. This happens in new projects as well as old ones.

