Which previous version are your rendering to that where Document dropped does not function because when you hover over a tabs Photoshop does not switch document so you you can not drop layer on it. I forget what version that was. I suggested version 21.0.3. Adobe first broke Photoshop WinTabs support in the 21.1 update. Adobe did not fix WinTab support in updates 21.1.1, 21.1.2, 21.1.3, 21.2, 21.2.1 and Adobe broke WinTab support in update 21.2.2 to the point to where pen pressure will not even function at all. Photoshop has always has issues with Windows INK support. Microsoft has to address INK operation features and performance.