Cannot download Xbox 360 profile after changing the gamertag. Error code 80151006

I created a new Microsoft account and thus an auto-generated gamertag was created as well. I downloaded the Xbox profile on both my Xbox One and Xbox 360. Since I wanted to change the gamertag to a gamertag over 12 characters long, I used my Xbox 360 to do so. Upon doing so, I was immediately disconnected from Xbox Live on my Xbox 360 and was requested to download my profile again. Before attempting to redownload it though, I checked on my Xbox One and logged on to my account on my PC and verified that the gamertag change had indeed worked and is now reflected to now my new gamertag.

But when I went back to download the profile on my Xbox 360 again, the following error message popped up after my profile downloaded about 1/8 of the way: "Sorry, there's a problem with the credentials that you're using to sign in. Go to https://accounts.live.com to fix the problem. 80151006" During the partial download, it even said "Hi, ______" (with my new changed gamertag).

I've gone to the site, signed on successfully on my PC but not sure what the problem is. I entered the exact same credentials when signing onto my MS account on PC as I did for the Xbox 360, but it still displayed that message on the 360. This message is also displayed when I try to do the same download on my Xbox One when attempting to play a backwards compatible Xbox 360 game. Once again, my new tag shows and I can play any Xbox One games completely fine with no issues. But it doesn't download my 360 profile for backwards compatible 360 games NOR does it work on an actual Xbox 360 console.

I tested this out on a second gamertag/account and got the same error. In both instances, the errors started once I changed the original assigned gamertag to my own personal choice gamertag. I have already tried manually adjusting the DNS, clearing the cache of the hard drive, clearing the MAC on my Xbox One, changing my MS account password, no 2-step verification enabled, restarting my console, power cycling it, and waiting a few days in between in case it needed time to update the tag change. None of these methods have worked. I know a few others have posted about this as well but their solutions did not work for me either or did not ever seem to be solved in the forum.

:)