Camtasia 9 Record button not working

If i start camtasia recorder - things work great, and I can then edit the movie, but if I then go to make a further movie from the editor by clicking on the Record button or use the File / New recording then nothing happens - the screen minimises but the screen record tools does not pop up.

I note that from the Task Manager the recorder is running and I have to manually shut it down and restart Camtasia if I want to make more screen recordings.

Is there something I can do to stop this issue?

I have seen some 'fixes' on youtube, which all seem to be something to do with a confilct with a Vorbis.acm file, but i have no Vorbis files on my system so I am unsure how to proceed.

Thanks in advance for any advice.
Dave

Ps - I am running Windows 10 Home. and Camtasia is version 9.0.5, but this has been happening for a little while before the latest update.