When using a Wacom tablet with Photoshop on Windows 10 the default behavior is to use Windows Ink. Unfortunately this causes problems in Photoshop, disabling Windows Ink fixes the problems but you will also lose the pressure sensitivity function on your tablet. The pressure sensitivity can be re-enabled by adding an entry to the Photoshop settings folder.
To disable Windows Ink open up the Wacom Tablet Properties window, you can access this via the Wacom Desktop Center or from the Wacom folder in the start menu. Go to the Mapping tab:
In the applications section select Photoshop and untick the ‘Use Windows Ink’ checkbox. Leave Windows Ink enabled for other apps.
To re-enable the pen pressure sensitivity you will need to create a new text document and add the following text:
# Use WinTab
Save this file in the Photoshop settings folder which is located at:
C:\Users\[USER NAME]\AppData\Roaming\Adobe\Adobe Photoshop CC 2019\Adobe Photoshop CC 2019 Settings
Name the file:
If you do not see the AppData folder click on the view tab and tick the ‘Hidden Items’ checkbox.
Restart Photoshop and you should have pressure sensitivity functioning again.