My current version is 15.3.0 (134456)
I am currently experiencing this issue in almost all of my files. Some do manage to upload (especially files with fewer pages, even when the file size is in fact bigger).
Sorry for the inconvenience this may have caused.
I believe that your problem is caused by a new defect in Acrobat Reader for iOS version 15.3.0.
The good news is that we already have a fix for it. The bad news is that the update containing the fix has not been released to the App Store yet.
Would it be possible for you to share a couple of your PDF documents that exhibit the problem with us (Adobe)? We can confirm that the problem is fixed with your PDF documents.
I sent you a separate private forum message with the instructions on how to share PDF documents with us.
Thank you for your help!
Thank you very much for sharing your PDF documents with us.
We confirmed the defect has been fixed in our internal build, which will be released to the App Store in the upcoming weeks, pending Apple's approval.
We will let you know when the new update (containing the fix for the defect) is made available in the App Store.
Thank you again!
We just released Acrobat Reader for iOS version 15.4 on January 23, 2016.
This release includes the fix for the particular defect that you have encountered.
Would you please give it a try and let us know if it works for you?
If you have trouble updating Acrobat Reader from the Apple App Store, please take a look at the following page for tips: http://adobe.com/go/updatehelp
Thank you very much!
This was indeed a bug in the app and was fixed in the latest release.