Streamline Theme: Custom input field not appearing when opening quick shop modal 2 times

Hi, I have a custom input field in my streamline theme, that also appears on the quick shop modal. The input field appears when changing “Length” to “Custom”.

The problem is, whenever closing one quick shop modal and opening a second product (second quick shop modal) the input field doesn’t appear.

The problem can be seen here: https://l09dte4lpzt983vq-28767944738.shopifypreview.com/collections/sneaker-laces

This is the input field: https://cln.sh/vDTsAf

The theme devs have release a help doc with the relevant JS events, but I can’t make it work. (https://archetypethemes.co/blogs/streamline/javascript-events-for-developers)