Thanks for your reply, Laura. Yes, I tried the Google Chrome browser on mobile and could not find a way to get the invoice payment link through that method as well. You say this is a limitation of the mobile app but could you please have your development team remove this limitation since it is quite necessary for your users? 

Also, we noticed that when we send a reminder email from the app of an overdue invoice, the custom message we created is not carried over from the desktop version. Instead it sends the messaging we use from a new invoice. This should definitely be fixed by your team and not be considered a limitation of the app as well. 

Thoughts?