Many parameter changes happen accidentally since the editors UI kind of interferes with the rotation and zooming features from the other editors, depending on whether a bone is selected or a constraint etc.
Lots of those changes can not be undone, the Undo buffer is empty. Currently I have to close the whole Unreal System and restart it just so that I get back to the last saved state.
This is really bad
There’s a discussion about that in here: https://answers.unrealengine.com/questions/418777/undo-history-is-extremely-unreliable.html
It seems that you have to disable the “auto save” to do the undo (if the engine save your state, you can’t execute the undo). It’s bad to work with this, but I’ll keep the autosave for project security.