APC40 Mk2 buttons stopped corresponding to Ableton Live

[luxxury]

Hi - I just bought Ableton 10 and opened a file that had been working in Ableton 9. The mappings are still there, but the hardware buttons and knobs no longer reflect what they are doing in the software. In other words if I press the 1 button on the APC, track 1 toggles successfully on my screen, but remains unlit on the device (though oddly it *does* toggle the 15th small light on the first knobs - which was not part of the midi mapping I made). I've turned MIDI off and on in Ableton, and gone through every combination in Ableton's preferences (MIDI input/output track/sync/remote) and nothing solves this. Any ideas welcome, thanks!

[S4racen]

Have you got MIDI mappings in the browser when you switch MIDI Mapping ON?

I'd delete and start from scratch...

Cheers
D

[luxxury]

Yeah, all the MIDI mappings are still there. It's a session I've been updating for nearly four years so it's pretty rich. Since the issue clearly started when I installed Ableton 10 I was hoping it was a known thing - like, "AB 10 replaces your midi prefs and here's how you can get them back to the old ones" or something. If scrapping it all and starting from zero is the only way so be it but I'd love to not have to!

***UPDATE****

Just did a Save As, selected all the MIDI mappings and hit delete. Restarted Ableton, plugged the APC back in, and it still has the same issue - buttons do not correspond to whats on the screen. Currently track 1, 2 and 4 are lit up in the SW but the HW numbers don't light up at all, even when toggling. Shit.