Have you tried rebooting the HE hub first?
Did you already have all these 30+ Zigbee devices paired to the Zemismart hub at the time when you successfully paired it to HE, or you added most of the devices later?
… just a shot in the dark, what could be the reason for this timeout error message that you get now.
The same problem 'Pairing failed @ FindOperational with code 50 (Timeout)' is mentioned in this post.
If you go to Settings -> Matter details, do you see the Zemismart M1 hub listed there?
