OLD Java Edition user cannot redeem to Windows 10

I bought Minecraft in 2011 and cannot seem to get my code for the Windows 10 version so that I can play with my nephew, who is on xbox one.

I'm getting this error:

"Error! It looks like we've temporarily run out of gift codes for Minecraft for Windows 10. Don't worry though, more codes should be on their way. Please check back later!"

I see that others have waited indefinitely for more digital codes to be generated, but it seems that this has slipped through the cracks or may be some sort of bug. I've searched for the last two hours or so for others who may have had this issue resolved, but only found people in the same boat as myself. They seem to be messaging Microsoft with no response, so I figured that I would try here with Mojang.