Acronis 2015 6055 true -image recue media

I am trying to backup my pc on my external USB 3.0
My 3TB HDD is seen.
My newly bought 5TB Seagate is not seen however.
Both are seen fine in windows.

I ran fsutil to see diskinfo:
Both disc seem to be the same:
Bytes per sector:4096
Bytes per physical sector:4096
Bytes per cluster:4096
Bytes per filerecord segment: 4096

So I don't get why the setup sees my other Drive and doesn't my new drive :(

It is no option to backup on my other drive as my backup is over 3Tb and I don't have that much space anyway to move around, it has to be on the 5TB HDD which I bought it for...