Reviving a slightly old thread, because I'm facing a similar problem when trying to do a nomination today (2 Oct 2022 @ 09:00 UK time).

The message I got was: "Sorry, we cannot complete your nomination due to a problem with our system. Please try again. If the problem continues, you can contact your Loyalty Service Centre to complete your nomination."

The message now no longer mentions a date on which the problem will be cleared. Has anyone faced a similar situation recently, and know what's going on and when it's best to re-nominate?