Submit a distributed form from mobile device

Hi Everyone, I have an issue with a distributed form. If I create the form (using prepare form in Adobe DC pro), and save it and send via  email it to a recipient, and they open it on their Pc/mac they can complete the form and click submit the form (on the top right of the doc)and it is returned and tracked and stored in the response file as is expected

But

if they open on a mobile device (phone/tablet ios/android they can fill in the form but there is no submit button, if I manually add a submit button to the form- tapping on this results in nothing happening - that is,no email client is launched or any action at all.

How to remedy this issue? The key thing here is using distributed forms to track and collect responses having people manually send a copy of the completed form is no use as it is not tracked and data is not collected in the response file.