Having a very strange, but not entirely unsurprising issue with Photoshop. The size dynamics of all brushes is always actuve. I've tried using the standard hard and sof round brushes (see the attached image) and there is pen pressure controlling the size.
Unchecking size dynamics and even selecting 'off; from the dropdown dows nothing. All the other brush settings can be changed and the brush window shows the previews as normal. Size dynamics is always on. Usin a wacom intuous and all drivers are up to date. Also updated to the latest version of Phososhop (23.2.2)
I've also tried the fix of creating a custom PSDUserConfig text file from this thread: