Perhaps you can send me your saved game and point out which AI firm is having the issue.

that make sense but it took for ever, and I was offering the same product with 1/10th of the price and still did not consider that. Also there was other companies producing it. so had more option than just me.

It seems that The AI is looking for a new supplier to supply the same product. It stopped buying from you because the deal was not good. But it also wants to keep the product on shelf while looking for a new supplier so that consumers wouldn't think that the AI has dropped the product completely.

I am not sure if this is by design or a bug,
I was producing product x and an AI store was selling it for me, then I noticed that the AI has stopped buying from me but my product was still on its shelf, I noticed that because I had changed the price in that city the AI company was loosing money so I guess it has stopped buying. I brought the price down with a huge margin left for the AI, but AI never checked that profitability of that product nor took it off its shelf.