no mountable file systems

[a-x-]

broken after first backup

but disk is mountable and I even can create and modify files on it and I can open timemachine image (mxtnr-mbp.sparsebundle) as a archive but I cannot mount it

[odarriba]

Not sure what will be happening here, but from time to time it produces some "invalid backup" error forcing to recreate the backup.

It may be related to some corruption on your storage disks, or even some strange bug in Mac OS - I have seen that even on TimeCapsules.

Does it continue happening on Mac OS Catalina?