Wanted to post the answer to this question but the site would not let me as it is a protected question?
The basic answer is it is your partition sizes
EFI = 260 MB Recovery = 1.2 GB minimums
See here
https://learn.microsoft.com/en-us/answers/questions/5516394/windows-server-backup-keeps-failing?page=1&orderby=Helpful&translated=false#answers
RNR