I've heard both, and the "-esseez" plural just seems less ambiguous on poor vide...

lxgr 9 months ago | parent | context | favorite | on: What's Going on with ‘Nonplussed’? (2017)

I've heard both, and the "-esseez" plural just seems less ambiguous on poor videoconferencing lines and recordings. "-esses" is a mouthful to pronounce.