I've had the same issue in the past. The first year of my garden experiment I purchased Wal-mart
tomato plants and ended up with huge wonderful plants with tons of blooms but never any tomatoes. Since then I go out of my way to buy plants from Farmer's Markets, and local plant sales. I think that the bigger retail stores are more about quantity not quality when it comes to seedings. (Who knows where the seeds originated from?)
My current tomato patch is doing pretty good even with our North Idaho late start- due to an above average snow year. I actually have two ripe red Glacier toms that I should pick tonight and my Siletz Tomato plant has about 6 baseball sized green tomatoes at the moment. This year I have 8 verities and all are at different stages of tomato production. All of my plants are now purchased as seedlings from local sources, and I have treated all past plants and current plants equal-with the same watering schedule, the same fertilizer, the same bees and butterflies, planted in the same place-the only major difference was this yearÃ¢â‚¬â„¢s bad weather prolonged start, which has not much affected this yearÃ¢â‚¬â„¢s crop.
My suggestion is to avoid those lusty looking Wal-mart tomato plants bursting out of their biodegradable pots beckoning everyone with the $3.97 price tag (I have to fight the force of the tomato dark side every time I am near the garden center each spring). It is honestly not worth the time and energy. As for Lowes I can't say, but it sounds like the same situation.
One idea that might work for your current tomatoes is to shock your plants (tell them dirty jokes about manure-ha ha err ha). An annual's only goal in life is to produce seeds. Your tomato plants might need to be reminded of this. You could give your tomato plants a severe pruning which might shock them into production mode (I know that this works well with dandelions). It sounds like you have a couple of plants to experiment with, so I just wanted to add that I've read to water non-producing plants with apple juice. Not sure about that one, but who knows. Best of Luck to you, hopefully better luck then me with those horrid Wal-mart tomato seedlings.
PS if all else fails return those dang things back to Wal-mart and get your money backÃ¢â‚¬Â¦