A new action as simple as: Case conversion "_ALL": Mixed Case, is leaving the following result:
Keep Movin (extended Version)
The problem is that first character after the parenthesis is not only capitalized but is changed to Lower case if already Upper.
This happens only if the action has been made in recent versions (at least v3.20 and v3.21). If I use the same action made several versions ago, it will work (!)
In that action you have to set the characters that determine a word boundary.
In your case you have to add the opening bracket.
To apply such an action to _ALL is a rather dangerous undertaking.
I doubt that the function has changed in the recent versions.