I don't have an answer but had the exact same problem this year. I injured my knee and wasn't able to dig so put tomatoes in container pots instead. Last year they were in the ground and we had tomatoes all the way until December. This year just a few of them and they didn't taste all that great. Like you I have peppers in pots in the same location that are doing great. Maybe the tomatoes are pouting in their pots.
All I can offer is my gardening motto "Oh well maybe next year!"