Update to 25.1 not installing plug-ins and bespoke workspace from 24.4

I'm having a similar issue. I tried importing one of my own custom workspaces, and it shows up in the "Export Presets" section (from the Edit > Presets > Export/Import Presets menu), but it's nowhere in the workspace drop-down in the options bar. I rebooted Photoshop and also restarted my computer with no luck.

The only fix I could find was to export the workspace, then re-import the one I just exported, and that seemed to work. But it was odd that it wasn't originally showing up in my workspace drop-down.

For your workspace you can follow these directions:

https://community.adobe.com/t5/photoshop-ecosystem-discussions/how-can-i-importing-a-custom-workspace-preset-into-photoshop-cc/td-p/8679499

For Topaz and Nik plugins - find your 24.4 plugins folder and migrate to the 25.1 location or simply reinstall them.