I have an automation rule on Tasks that has an action that edits the issue and copies some field from the Epic to the Task. It works. However, recently I opened the rule and the UI does not show that the field is copied from the Epic. Instead it shows the field to be set as empty (with "Type to find value..." written).
Again, the rule works fine, and copies the field from the Epic, but when opening the rule's configuration, it is missing the information on how the field is set, and this is problematic (as it makes it very difficult to maintain the rules).
This happened to us on at least three different rules. It seems like all of the cases were related to copying the field from the Epic.