Hello @Deadlyo0 ,
From what the log shows, it looks like the editor is trying to access something that is null or no longer valid.
This can happen if the Timeline is trying to update a variable or a component that no longer exists or was renamed, or if it has the same name as a function or a variable inside the same Blueprint, which can sometimes cause conflicts when the editor tries to open or modify the Timeline.
If none of the above applies, do you still get the same error if you create a Timeline from scratch?
How are you creating it in your Blueprint?
I’ll be waiting for your reply!