Time Machine "exclude these items..": external hfs+ hard disk greyed out
Hi there,
Big Sur, Time Machine is working fine backing up the internal Macintosh HD to a newly formatted APFS external hard drive.
But I have an additional external USB 'data' drive that I want to include in the Time Machine backup.
In System Preferences->Time Machine, when I click options to remove it from the "Exclude these items from backup" list, it is grey.
The external 'data' hard drive is HFS+ formatted.
I understand to an extent that there's big changes in how Time Machine backs up in Big Sur.
I suspect TM will no longer backup HFS+ volumes. Can anyone confirm that this is the case?
Many thanks in advance.
iMac 27″, macOS 11.2