Yes I have tried manually installing OS3 apps. The error message is “this is an OS3 app and is not compatible with OS5”.
Also, SSH has been altered and I can no longer SSH into the nas.
This graphic released by WD shows more clearly what you are losing compared to with OS3 to OS5. As you can see there are virtually no apps.
https://support-en.wd.com/app/answers/detail/a_id/29389
You also might want to chekc out this if you use transmission as they were clearly targeting its use in this update.
https://community.wd.com/t/my-cloud-os-5-transmission-app-issues/259198
