since upgrading to High Sierra on my MacBook Pro laptop, time machine won't back up to my external drive. It says I must turn off Firevault, which I did yesterday. Now my Mac is tied up decrypting, which has been going on for 24 hours, and still has 14 hours to go. Is this normal? Is this necessary now everytime I want to back up? Please help! Also, I need to use my computer for work tomorrow. How can I pause this process, or can I work over it?