Is it possible your bank or credit card company may be denying your ESO Plus purchase? I'm also wondering if ZOS hasn't fixed it fully yet. Or it's slightly possible your purchase was successful, but you only received part of it. I encountered this issue when I bought Dying Light + Season Pass a while ago, it approved the Season Pass & the game, but I only received the Season Pass and had to go through hell with customer support to get my darn game code. I get these are two very different things, but it's the only similar example I could think of that I dealt with in my short time with Xbox so far. Good Luck Just keep trying with Customer Support until you get what you are owed.
Man, that sucks! I was a victim of this issue last August-October, and I did receive my Crowns after submitting support tickets. Even got extra when they announced they had resolved this issue.
I've gotten Crowns every month since, but I've been having issues now with losing my in-game benefits and access to the DLC. So, I'm letting my ESO+ membership expire. Sad, really, since I've been a monthly subscriber since PC early access.
But, the in-game benefits aren't enough for me to justify the monthly expense, and I can get Crowns cheaper via the Crowns Packs (well, at 3,000 and 5,500 allotments). I've already purchased Orsinium and will just purchase the future DLC I'm interested in.
Unless ESO+ provides additional benefits in future, I'll remain unsubbed. I just don't want to deal with the hassle anymore, especially since there are people who are still not receiving their monthly Crowns, and it's possible I'll get hit with that issue in future. I already lose access to content/in-game benefits from time to time.