In my experience, most discrimination is subtle. For 18 months, as the only female sysadmin on a team, I was routinely left off of important email chains, "forgotten" to be invited to critical meetings, not given access to important tools to perform my job, and asked to perform secretarial duties for my male counterparts. Any suggestions I made were met with "thanks for the input, but we are going in a different direction". Weeks later, one of the males would be praised for coming up with the same idea i had proposed earlier.
We have multiple trainings telling us how not to be overtly sexist. What they don't cover, is the common micro aggressions that are easily overlooked. Were my coworkers overworked? Yes. Do things get overlooked? Yes. Can you forget one person on a team of 5 for 18 months straight? No.
I work with 720's on a regular basis. I've not seen this particular issue, but I would look at the logs first, then look to see if there is a bios update available. Can you go in through iDRAC and see if those vdisks are there, or if it throws an error as well?