I'm afraid I don't exactly understand the scenario.
You are inserting into two tables. It looks like your page has ProdType, IndustryType, and ProdSize.
Can all three of those have multiple selections? What two tables are you inserting into and what values would be inserted? What is the live URL where I can view the page.
Once you have a repeated form element it should be selected from the value dropdown, not from the lightning bolt.