Found two issues on Illustrator 25 and Photoshop 22 (CEP 10) on macOS with a secondary monitor connected. I have attached a simple CEP extension for Adobe to investigate the issues. Download the zip file from
Reproducible steps are included in the extension itself (See image below). Both are critical issues affecting all CEP extensions including Adobe’s own “Library” extension across multiple Adobe 2021 apps (e.g. Illustrator, Photoshop, etc.). I hope Adobe can move quickly and have a fix for those issues.