Can't remove a drive from "Excluded from Back Up" list in Time Machine - reopened with solution

Original post was in 2020 by another member of the community. It was closed for updates.

External drive in "Exclude from Backups" is greyed out so cannot be removed from exclusion list. In other words, Time Machine doesn't back it up.

To fix in my case, renamed the drive from Video to VideoMine.

Though how it then backed up 3 TB in under a minute, I don't understand. An ASUS/Intel VROC with 4 Samsung Pro SSDs can run almost that fast but not a single EVO drive connected to USB and certainly not write that fast to a hard drive. Must be magic. And yes, all the files are on the Time Machine backup. Perhaps some expert out there can explain what was going on regarding the speed of the backup. My guess: the exclude was ignored and the drive was actually being backed up all along.

Hardware:

4TB Samsung EVO SSD in OWC USB-C external enclosure

USB-C connection to CalDigit 4

12TB Western Digital external drive for Time Machine also connected to CalDigit 4

CalDigit 4 USB-C connected to 2023 MacBook Pro

CalDigit also powering the MacBook through USB-C