1. Place a signature in a PDF document using Acrobat Reader on iOS (v12.1). Save signed document as PDF_A.
2. Open saved document PDF_A with Acrobat Reader in Windows 10 laptop. Can view the signature.
3. Place another signature in the opened document, save the PDF as PDF_B.
4. Open this PDF_B having two signatures with Acrobat Reader in either iOS or Windows, both signatures are visible.
5. Open same PDF_B with Acrobat Reader in Android (8.1.0, MIUI 10.0.2.0), can only see one signature only which was created in Windows, but not the one created in iOS.
6. Place another signature using Acrobat Reader Android, save it as PDF_C.
7. Open saved PDF_C using Acrobat Reader in Windows and iOS. Now can view only signatures created earlier in Windows, and in Android.
8. Even if use Acrobat Reader Android to open PDF_A, it can't see the signature.
9. If we sign and save a new PDFD using Acrobat Reader Android, use iOS Acrobat Reader to open PDFD, one can see the signature.

Looks like there's a bug in Acrobat Reader Android that makes it unable to view a signature placed in a PDF document using Acrobat Reader iOS.