Updating to 6.4.1 broke the shop

-- HikaShop version -- : 6.4.1
-- Joomla version -- : 6.1.0
-- PHP version -- : 8.4
-- Browser(s) name and version -- : all
-- Error-message(debug-mod must be tuned on) -- : No size selected

I just updated one of my shops to Hikashop version 6.4.1, coming from 6.3.0. Technically, the update went well, but after testing an order, it turns out that my shop does not work anymore. This may be due to the set-up I have. For historic reasons, my products have their options setup as custom fields. Reason, years ago, when the shop wat set up, it was not possible to have a variant/characteristic set up without having any of the options selected. With custom fields, this was possible, so I created a custom field for every product I have (Table:Item, Single-dropdown). See a screenhot for a random custom field. Note that I am perfectly aware that this is not the advised set-up, but still, this setup should simply work.

Until the update, this always worked perfectly well, but now it does not anymore. When I select a size on the frontend, I get an errormessage as if I did not select a size yet, see the screenshot.

If needed, I can grant access tot he dev-site where I tested this, but I presume this can easily be tested on any environment.

Dear Nicolas, yes, that appears to be the issue. Removing the overrides fixes the issue indeed.
Thanks!