I've created a Custom Subtab for Item record called "Extra Details". I want to add Field Grouping so I can display the fields with some headings. When I am in Custom Entry Form customization >>Fields Groups >> Extra Details I do not see any lines for add Field Group Labels. Going to Main, Purchasing etc shows the Field Grouping labels as expected. can I ever add Field Grouping to custom subtabs? SA is not helpful on this one.

Navigate to the custom form itself (I usually get there by viewing an example transaction, and then selecting Customize > Customize Form in the upper right, that way I make sure I'm always selecting the correct form I'm thinking of) On the custom form, select the Field Groups tab. You should see a whole bunch of subtabs where you can add the field groups for each subtab. Sometimes it extends beyond the usual page size and you have to scroll right if you have a lot of subtabs.

@James Morris yep, i'm aware of that. specifically I am asking about a custom subtab. Create a new subtab, Customization> Forms> Subtabs> New. It's that new subtab that I want to add Field Groups

So you created a subtab, but it's not showing there? Is it showing on the form in the transaction/record entry UI?

Cool. I check this morning and now it's there. Maybe I just had to have patience. I already had the fields there.

Nice. Glad it's working! That seems to be how it works at my company too. Once someone asks me about the problem it all of a sudden starts working 😆