Inconsistent Time Machine backups

crashmeister wrote:

The issue is that the backups are NOT alternating drives.

As of this post, all backups for Nov 03 are on TM-2 (10 of them) and ZERO are on TM-1.

I believe this can happen because the target Time Machine drive appears to not be available. See my list of candidates for how or why this can happen in my earlier reply to your post. It is usually some sort of issue (which can be intermittent) with the external drive or its cable.

For instance, some users have reported that one or more of their external drives can briefly disconnect (unmount) and then connect again, on their own. Typically a cable problem, but can be other things as well, usually hardware. Or a drive sleeps due to its settings. I use a Samsung T7 and never have seen what you are seeing. But I recall that T7 came with some proprietary drive management tools from Samsung. I erased and formatted the drive and never use such third party tools, but some have reported oddities when such tools are installed or utilized, including vendor firmware. Some Samsung drives have "one button" touch activation which requires that custom firmware or tools be installed. If you are using your T7 as a generic drive with no third party tools, then obviously this does not apply to you.

It is still November 3, can you check Time Machine Settings by inspection and see if both drives show as mounted, both should show "Next Backup: Automatic (hourly)" and then watch what happens when the next scheduled backup (one hour from the last one on either drive) should occur on the drive that is getting no backups, is there some error notification or what happens. Is it mounted and stay mounted.