My external drive does not show up in Time Machine
I use Time Machine with an external NAS with no apparent issues. I have an external drive that I want to back up to Time Machine when it's connected to my laptop. I have no excluded directories in my config, and the "estimated backup size" is the total of my laptop's internal drive plus the external drive. So far so good.
However when I enter Time Machine and go back in time a bit, the external drive (while plugged in) is greyed out. The external drive is not always connected, but I waited for a couple of backups to complete before trying this.
What's the problem?
Thanks!
MacBook Pro (2020 and later)