Whoops, forgot to mention that I checked the cycle_info.txt file too!
When I had selected the 2013 AIRAC, then pressed Restore from the dropdown list of AIRACs on the right of the X-Plane add-on line, it was as if nothing happened, no indication that any task had been performed.
If I used the Restore button on the upper part of the Data Manager (after selecting X-Plane 11.50), I did see another icon appear below the Sort button and alongside the X-Plane 11.50 line, a split second it appeared, impossible to really know what its indication was for.
Anyhow, for now, I do have 2013 loaded, which gets me around the Zibo issue (I am running a very old Zibo 3.35.6 and he only fixed the latest version) so I still get to fly!
As an aside, I noticed while looking at the restore function that the Data Manager backup index seems to have my 2011 cycle header wrong, you can see via the picture I attached as well as these lines from the backup.index file. Never caused me any issues, just curious what may have caused this.