Mobile UI issue -- PDF UI diappears

We are getting a error in Mobile device wile trying for adding Signature
Condition 1 : Add New Signature , Draw the Signature , Not Placing the Created Signature , but trying to add the New Signature , The PDF UI be comes Blank

Condition 2 : Add New Signature , Draw the Signature , Placing the Created Signature, Then Remove Signature , Then Add New Signature , The PDF will disappear

This scenario is found only on Mobile devices