I am facing the same issue. On my M2 MBP, the predictions are showing. But on my new M4 MPR the predictions stopped appearing since 4 days.
What I tried:
Enabling/Disabling predictions, Many Xcode restarts
New Projects and existing one both don't get predictions
Delete Derived Data, Caches, Config files...
Re-install Xcode
Reset the Mac completely to factory settings and reinstalled everything (Same)
I am suspecting maybe Apple disabled the model remotely on M4s?