Last night SFO-PHX on a Max9 I got to the gate during Group 5 and they were forcing gate check. I had a brief discussion with GA who was scanning BPs about whether front cabin overheads were really full b/c IME the new space bins pretty much never fill in the front cabin on a Max. She responded "they're telling us it's completel full" and insisted on tagging my bag but finally said "you can check with the FA." The helpful FA at the door took a quick look and sure enough, there was a bin right over my row (2) with only one bag in it.