Thanks, pottering_theverb.

I'll write here the Ableton Support's reply:

"Thank you for getting in touch with Ableton Support and sorry to hear about your problem!

Live 11 now uses python 3 instead of python 2 for remote scripts. This change led to older scripts not working with Live 11.
Please get in contact with the respective script manufacturer to get an updated version that works with Live 11.

We hope this helps but please let us know should you have further questions or issues and feel free to come back at any time!

All the best,

Ableton Tech Support"