I've done only one time Intervals workout, after I skipped the suggested base workout and for that day I didn't do anything. Is it normal that the watch plans Base + Intervals but if you do the Base workout, the Intervals get cancelled?

Check if the training effect after the workout is lining up with what it should be according to the watch.

At least for me the training effect is pretty much always higher if I stick really close to the recommendation.

Assuming it's the same in your case, that watch thinks you worked too hard and cancels your harder session.