Hello,
With the available information, its quite difficult to answer the cause as lot of factors can lead to such situation like legacy or UEFI boot . There are limitations in Legacy boot mode where Max size of the partition has to be less than 2TB .UEFI doesn't have any such limitations.
In case if the server is in UEFI and the issue is the same we will have to investigate the cause . We will suggest logging a ticket with HPE support team to investigate the issue with the supported logs.
Regards
