Linear VS Musical MIDI bug?

Hi there. I’ve just encountered the strangest thing. I know about the problems regarding some projects not allowing you to move MIDI information in linear mode depending on how the project was started etc.

I managed to start a new project and have my MIDI information move successfully with the cursor while making tempo changes. But then suddenly- it started behaving as if I was in musical mode. I checked and the orange icon was lit for linear. But then AS SOON AS I WOULD START ADJUSTING THE TEMPO TRACK, THE BUTTON WOULD CHANGE TO THE GREY MUSICAL MODE! As soon as I release the cursor, it will return to linear…

Nothing I have done can now get it to behave in linear mode. I have no idea if I had triggered a setting (I’ve only been on the main window and working in MIDI mode.)

Anyone else ever encounter this? Or am I just being stupid? Very frustrating.
THANKS!