just tested here and I was able to use the suggest without losing the sync. While the sync is active I was able to drag chords or fill the pattern and the follower replicated the changes from the leader.
Changes in the follower instance can turn off the sync, creating a pattern or editing a chord will get the follower to stop syncing. Make sure the follower is still in sync before starting the suggest mode in the leader.
Changes in the Leader using suggest resulted in updates on the Follower. You cannot make changes in the Follower and have the Leader change. That is not at all what it is designed to do. Leader leads - Follower Follows Leader.
You said it right here. In any event I tried
Using suggest in the Leader changed a couple chords and Follower updated and sync still active. That was in Bitwig.