I encountered the same problem.
I turned off BitLocker on both the 980 Pro 2TB drive and the system drive, which is a Samsung 512GB NVMe. On Windows 11: Control Panel > System and Security > BitLocker Drive Encryption.
Magician then performed the firmware update as expected.
You might be able to simply pause BitLocker.
Samsung Magician should be able to do this automatically, or at least notify you to pause BitLocker.
Of course, it is a good idea to backup your data before performing a firmware update.