Hi,
I'm Sumit, here to help with your query on the Microsoft Q&A forums.
Apologies for any inconvenience you are experiencing. I am happy to help you today.
It seems like it is broken from Microsoft end.
Standard troubleshooting steps from MSFT:
First, make sure you have this feature turned on. On your PC:
Open the Phone Link, go to Settings > Cross-device copy and paste, and make sure the toggle is On for Allow this app to access and transfer content I copy and paste between my phone and PC.
If you tried to copy a large section of text and it didn’t paste on the other device, it’s likely to have exceeded the allowable amount. Try copying and pasting smaller sections between your devices.
If the feature is already turned on but you’re still unable to copy and paste content, there may be a connection issue between your Android device and PC. Try closing both the Phone Link on your PC and the Link to Windows (pre-installed) app on your Android device. Reopen both apps — your most recent messages, photos, and notifications should be visible in the Phone Link on your PC if your connection is working normally. You should now be able to successfully copy and paste your content again. As a last resort, restart your PC and try again.
Note: If you're using Microsoft Edge, make sure to update to the latest version of the Edge browser.
By any chance, did you try syncing using Swiftkey keyboard? It is working OK for me.
I hope you find this information useful. If you have any more questions, don't hesitate to reach out. Otherwise, please take a moment to rate the thread. Wishing you good luck!
Standard 3rd party link disclaimer:
There may be links to non-Microsoft websites that provide accurate and safe information. Watch out for ads on websites frequently classified as PUP (Potentially Unwanted Products). There is no need to buy paid products to fix your computers, as they sometimes do more harm than good.