External SSD switching to "read only" when used for TimeMachine backup

[vs40]

I got new external SSD and want to use it for Time Machine backups, but it switching to "read only" after configuring the Time Machine.
SSD is working, I can format it in exFAT or APFS and use like normal external drive, but right after selecting it for Time Machine, it switching to RO.
I'm tried to reformat it, running First Aid in Disk Utility and restarting my MBAM1, but still the same problem.

Any ideas folks?

 

[Weaselboy]

I'm seeing the same thing, so I'm guessing that is normal for an APFS TM backup drive,

 

[vs40]

I'm seeing the same thing, so I'm guessing that is normal for an APFS TM backup drive,

It makes no sense ?
I got 1TB drive not only for backups, but as external drive as well.
And I was using my previous one like that with my old MPB, but it has "Mac OS Extended" formatting.

 

[Weaselboy]

Have you tried using Disk Util to make two volumes, one for TM and the other for your storage like you want. I have not tested that, but I think it would work.

 

[vs40]

Have you tried using Disk Util to make two volumes, one for TM and the other for your storage like you want. I have not tested that, but I think it would work

Thanks! I didn't knew APFS volumes are flexible and I don't need to cut them in to defined size disks.
It is still little bit unusual to work with two different mounted disks instead of one, but it works)