Does turning off »Use Graphics Processor« in the Performance Preferences (Photoshop > Preferences > Performance > Graphic Processor Settings) and restarting Photoshop have any bearing on the issue?
Could you please post screenshots with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible?
Please read this (in particular the section titled "Supply pertinent information for more timely and effective answers”):
https://community.adobe.com/t5/using-the-community/community-how-to-guide-tips-amp-best-practices/td...