Try booting your Mac in Recovery Mode; it can finish encryption of your Mac for you. Hold down Command-R while you turn on or restart your Mac. Release the keys when the Apple logo and a progress bar appear. Plug your MacBook into power to ensure that it can resume encryption of your hard drive. When the Utilities menu appears, go to the very top of the screen and click on Utilities, then choose Terminal. Execute one of these commands:
diskutil apfs list (If your MacBook uses Apple File System or has a SSD)
diskutil cs list (If your MacBook doesn't use Apple File System)
If you used the first command, look for Macintosh HD in the list and check the status for FileVault. If it's still encrypting, it should give you a percentage of how much of your Mac has been encrypted. Periodically repeat this command to ensure that your Mac is actively being encrypted. When encryption is complete, the percentage should disappear. Quit Terminal and restart your Mac.
If you used the second command, scroll down to the Logical Volume Family and check the conversion status. It may or may not show you a percentage. Periodically repeat this command to ensure that your Mac is actively being encrypted. When encryption is complete, Conversion Status should report Complete. Quit Terminal and restart your Mac.
If you authorized your Apple ID to unlock FileVault, and want to test whether you can reset your password in case you forget it, execute resetpassword in Terminal. Choose I forgot my password, and you will be guided through the steps of resetting your user account password.
Hope this helps!