Invisible fast review button stuck?

Hi

Beta 17.0B build 23
I've been having a problem with timelines running at three and four times normal speeds
I thought it was someting to do with high frame rate timelines but now I think I have worked it out.
I believe that the "fast review" command has been hit and locked by some accidental kestroke, and I can't find an icon or a menu command, or indeed the keystroke to reverse it.

Does anyone know anything about this?
Does anyone know the keyboard command to start of stop Fast review?

Many thanks

Alan Mahon

To use the Fast Review feature on your Edit Page timeline, select Playback > Fast Review.

Pressing K or the spacebar will return you to the normal JKL playback mode. If you use this feature often you can bind Fast Review to a specific key in the Keyboard customization window.

There is a fast review button at the bottom left of the playback window on the cut page as well.