It sounds like you've done everything you can and it's great that you've gotten a response (hey, that's a start).
While I don't have any inside knowledge I think I can envision some idea of what might be happening. When Dirty Tesla (
@DirtyT3sla) of YouTube fame got a new vehicle he was able to get the beta on the new one but he did have to wait for a new version to be pushed out.
Tesla has been very cautious in pushing out new versions ever since the 10.3>10.3.1 debacle. I know this is a technical term but I believe they have a case of the heebie-jeebies
. Since they are being cautious they are severely slowing the release pattern. The current 10.6.1 has only gone to a relatively small group of previous beta testers. My guess is that the next release that gets a full release to all previous testers should get pushed to you as well...at least I hope that's the case. Good luck!