Rename not working

When in Details mode I can no longer get into file rename mode by clicking on a file, then pausing and clicking again. I now have to use right click and select Rename form the context menu.
In other view modes (eg: list) this works fine.
What have I done? :question:

Does pressing F2 work?

Are you definitely in Details mode and not Power mode?

Are you clicking on the icon or the filename? Only the filename part will let you rename.

Pressing F2 works. Definately in Details (not Power) mode. Am clicking on the filename, not the icon.
This is on my USB copy of the app. The full install version seems to work OK. The USB export used to wok OK till a few days ago.