Mailchimp embedded form doesn't work on mobile phone

Hi!

I’ve created a landingspage with an embedded Mailchimp form. This works perfect on a desktop. After filling in the form:
– I come on my ‘Thank you Page’
– I’m added to my audience with the right tag and the source is embedded form

But….
When I’m using my phone (Apple) this doesn’t work. I do come on the Thank you page but the import in my audience doesn’t go well.
It says ‘hosted form’ as source and then the tag doesn’t work.
My friend who has a Samsung Phone doesn’t have this problem. She comes in via source ’embedded form’ and the tagging goes well.

How can I change this?
I’ve added the html code in the private content field.

Thank you.