upload error from GoogleDrive via Android

"Upload error" with all sorts of files (Ex.: PDF, JPEG, etc.) when uploading from GoogleDrive to Seal via Android. 
Seal app behaves in a strange & random way: some files are uploaded successfully after 3-4 attempts. 
Detected this bug during manual tests of Seal app. 
Could NOT identify clear patterns & reasons of this bug after multiple attempts. 