The recommended meal shouldn't open a menu, it should just select a couple of items at a slightly reduced price.
The menu I think you're taking about is for meal sets; as you have more meals you'll eventually stumble into one that gives you a small buff in the next battle. It will then be added to that menu so you can remember it and select everything quickly. Don will occasionally suggest them, though I can't say for sure whether he'll go through all of the ones available in his bar.
If you want to fish for meal sets without spending all of your money and overfeeding your crew, you can select combinations of 2 or 3 food items until a name appears under the menu but at that point you may as well just look them up.

When I click on the recommended menu button, nothing gets selected. It remains blank and says cost of 0. I tried it multiple times and even the textbox in bottom left is hinting he trying to suggest things but nothing is suggested. I know about the meal sets. Those work fine. It's HIS recommended dishes not working.

Do you have any party members selected? That's the only other thing I can think of. If you do and it says it costs 0, I'd send your logs to Dandylion. It works for me, so sounds like there's a bug somewhere.

I tried it again later yesterday and his recommended menu showed up. I don't remember what I did. I'll observe again later when I play again.

I'm having the same problem, neither him nor the bartender recommend anything, this was since the beginning of the game and now through all of the sets unlocked, from 1 and now 5 selected characters. this is on both my desktop and laptop. never once has anything been recommended.