Hi,
1.Have you tried to reboot the mac and reconfigure the .rdp file by exporting and importing again?
2.Instead of using .rdp file, please also try to set up user account and save credentials in rdc for mac.
- Go to Preferences, click on the "User Accounts" tab and select the connection that is saved. Enter the password in the Password field where it says "Optional".
- Close the window and now you will not be prompted to enter the password again
3.As below thread indicated that the saved credentials should be stored in below path:
/Users/$USER/Library/Containers/com.microsoft.rdc.mac/Data/Library/Preferences/com.microsoft.rdc.mac.plist
Applications/Utilities/Keychain Access
https://learn.microsoft.com/en-us/answers/questions/159746/microsoft-remote-desktop-password.html
https://support.apple.com/guide/keychain-access/what-is-keychain-access-kyca1083/mac
Hope this helps and please help to accept as Answer if the response is useful.
Thanks,
Jenny