I currently have 2 apps downloaded for my store. Infinite Options and Zakeke. I sell engravable watch bands and give customers the option to add a color fill to the engraving of either white or black for $5.00 extra. I have this extra charge built through the Infinite Options app. When I sell a pre-made design on my products page, the Color Fill Charge is added to the cart; however, when I have a customer select the color fill charge and it's color and then customize their own band design, the color fill charge doesn't show up the cart? What can I do to fix this issue?
Try to contact their support. I hope they can proivde you the solution.
If do not get the solution, you can try Inkybay instead. Inkybay comes with extended product options as well where you can charge extra for any selected options from the product page. And you will not need an extra app for product options in this case. Inkybay comes with both product options and customization.
Here is a demo with product options, you can take a look.
If you need any help or assistance, let me know.