[Q] CORS POST doesn't work in iframe on Samsung devices topic

I posted this under Java even though the app is an Ionic app because I don't think the problem lies in the Web-part of the app, but in some configuration part of the app that is not handled by Ionic.

I've developed an online store app which uses DIBS Payment to offer the customers to pay by credit card. The credit card form is hosted by DIBS, and because of that we show it in our app in an iframe. To load the credit card form, we post data to an external url that runs off of the HTTPS protocol. The credit card form is shown, but when the customer pressess the "Pay" button, the iframe content gets blank and nothing happens. I've debugged the app using Chrome inspector and I can see that when the user presses "Pay", they are supposed to be redirected to a new page through a POST request. However this POST request is never finished, it freezes at "Pending". This POST request is to another domain than the first domain loaded in the iframe. I think this is the issue somehow.

I've found that this error only occurs on Samsung devices. I've tried on a Nexus 6, Galaxy Nexus and Genymotion emulator where it works as supposed. However on Galasy S4 and Galaxy S6 Edge, nothing happens but that the user gets a blank screen after pressing "Pay". What could cause (probably) only Samsung devices to do this, and how can I solve it?