DJM-900 NXS2 and Ableton Midi Sync

Hi there,

I've been experimenting with trying to get my DJM-900 NXS2 to sync with Ableton, using the PDF guide linked to in this earlier post:

https://forums.pioneerdj.com/hc/en-us/community/posts/205650573-DJM-NXS2-Ableton-Sync

My setup:

- Ableton 10 on Windows 10, with latest Pioneer driver installed.

- Mixer connected with USB.

- DJM/CDJ connected with DJ Link using an Ethernet switch.

- Rekordbox also connected with DJ Link (just to load tracks) 

I've managed to get Ableton to sync with the BPM value from the mixer.

However, when I click EXT in Ableton, even with clips/scenes in Ableton armed to play in session view (green, flashing) and pressing MIDI ON/OFF on the DJM, I cannot get Ableton to start playing.

What am I doing wrong? The earlier posts and the PDF guide suggested to me that this should work :)

Thanks,

Alex.