[Solved] 'Add Action' Missing from Event Sheet

My apologies if this is a silly question. Recently 'Add action' went missing from my project event sheet. I can add events, but there's no way to add actions to events.

I can add actions just fine to previously saved versions, so it seems to be something I've done to the latest version that's caused it, but I can't figure out what it is or how to fix it.

I scanned the manual and forums for this but haven't found anything. A pointer to resolve would be much appreciated. (If it's at all relevant, my layers are all visible and unlocked.)

Answering my own topic for the benefit of anyone who makes into the same mistake.

At the far right of the Events tab (to the right of the Search bar) is a checkbox that says 'Show 'Add Action' links. If this is (for example accidentally) unchecked, 'Add action' will not appear in the Event Sheet. Just check the box again to re-enable Add Action links.