Please try the suggestions made by @PrimePixel . If the issue persists, please send us an error report from the Samsung member’s app -> Beta Feedback -> Error Reports. We apologize for the inconvenience and appreciate your contribution to the beta program.
One UI Beta Team
Thank you very much for your feedback.
We sincerely apologize for the inconvenience.
TV mirroring is not supported in current SmartThings1.7.89 due to P2p API change of T OS
It will be fixed in next app update - SmartThings 1.7.91