you expected a microfocus backup product to support the backup of a microfocus os.
There is no support for SLES/OES with data protector GRE
Several os types that OES default use, like NSS are not supported in combination with GRE.
if you have a complete windows environment, than it seems you can use the full potential of Data Protector, but when you are running the environment on microfocus products, like us (SLES, OES 2018, NSS) than the only option you can use is traditional file backup.
You can make vm backups but than you can't restore induvidual files, but than you have to backup twice one vm backup and one file backup and there need extra time and storage.