Hello,
Thank you for posting in Q&A forum.
To troubleshoot this issue, please kindly follow below steps:
1.Please check if the label file you imported is encrypted.
2.Copy the file into a new one and make sure file is readable.
3.Import the label file into Microsoft Information Protection page again and check if it works.
I hope we can help you solve the problem. If there are any misunderstandings, please feel free to let me know.
Best regards,
Jill Zhou
If the Answer is helpful, please click "Accept Answer" and upvote it.