In 2025, press F10 and confirm all the "path" are correct - System file path, Option path, Data Path.

Delete the 2025 clients. Restart the computer. Go to 2024 and transfer again? Try just 1 client to see if it works. If a success do the next one. 

That would be my best guess. This is a user support site.

If this fails, call support. Contact Support has the phone number.