Adobe Acrobat X Pro - Filled out fields not showing on mobile devices in email clients?

I designed a new invoice form in InDesign and exported as a PDF. Then in Adobe Acrobat X Pro, I added the necessary fields and saved. Now, when someone fills out the invoice and emails it back to me, I can see the filled out fields on the form when I view from my desktop (iMac & Gmail) but when I try to view the PDF from a mobile device such as iPhone and iPad, the original form shows with none of the fields filled out. This is quite the issue because when accountants etc. Try to view it from their mobile, they just see the blank design. Help!

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