Got this response from support after I reached out to virgin via a few different channels:

I’ve been in touch with our Flying Club team, and they have informed me that there are ongoing issues with Aeromexico reward redemptions, which are currently on hold. They are aware of the issue and are actively working to resolve it.

Unfortunately, we do not have a specific timeline for when these reward seats will be available again, but we truly appreciate your continued patience and understanding as they look into the matter.

Thank you for your cooperation, and please don’t hesitate to reach out if you have any further questions.