Ideas
I just came across the same issue last night. After working hard to save up enough money for my sim to purchase a retail shop to run as a bakery it refused to work. I could mark items for sale but the tags were pure white (no $ symbol or price listed) and while customers came in they only stood around and talked, no one tried to buy anything. My sim and his husband were actively running the business and while they had some retail conversation options there was nothing available to "close the deal", etc. I let it run for hours without a single sale. Many of the goods were excellent quality and I had no mark-up on the items.
I do play with mods but I took them all out and cleared my cache with no change to the behavior.
I have played a little bit with retail stores years ago so I had a high level idea how it should work and I knew this wasn't right, then I found this bug report.
This is very disappointing. I had a whole life plan for this sim where he was supposed to work his way up from a Home Chef Hustle bakery cart to a real brick and mortar store and now that won't be possible unless I re-enable Businesses and Hobbies which was not the plan (I wanted to revisit the GTW retail system as part of my deep dive into the aspects of GTW that I hadn't done much with).