When encrypting or decrypting a drive with Encryption Desktop, the process does not start or resume. This occurs following enrollment or after a Windows restart.
This is by design. Encryption or decryption will only start or resume if the computer is connected to AC power.
If the computer switches to battery power during encryption or decryption, the process will pause automatically and resume when the computer is connected to AC power.
Connect the computer to AC power.
Note there is a feature available called Force power failure safety. This allows Encryption Desktop to recover if there is a power failure during encryption (though encryption takes longer). However, this option does not permit encryption to start or resume on battery power.