[Android Apps and Games] 8milerd:
I am will not say with 100% certainty but it may be as simple as a permission or ownership issue or as stupid as a thumbs.db or similar file or flag being placed on or in it causing what I assume an app such as this would have, at least one would hope it would... A tampering check, example being SHA/MD5/? check sum mismatch?

WITH THAT SAID:

Red flag #1: Closed source

Encryption is one of those things... Never, closed source. Never.

Red Flag #2 Bait.

1GB free then a "PRO" edition with more features allowing more private data to be encrypted with Unlimited storage... more storage. Storage where, what servers if none, whom has access him and that app and you, how do you know, how can you ever know, other than the word of the Dev? That's a lot of trust to place in some man/woman/organization from what I assume, is in India.

My money and my guess will be the Intel services of that country and thus Russia, Brazil, China and who knows how many more.

Or it could be 1 of more than 150 many working hand in hand in these increasingly & historically fluid times between historic allies and enemies.

There are very few things 99.0% of your everyday average users want to encrypt; pics of places or people that they want to keep from a spouse, likewise for say text doc, word docs chat logs and/or apps.

10% of the 90% possibly those spreadsheets or presentations that contain company info or to keep company eyes off the fact they are using a company phone for other reasons or whatever, doesn't matter.

The other .99% would be intel, military, other agencies and various contractors. None of whom would use this and if an employee did with a phone owned by them, well, many countries would likely whack them for such foolishness.....

All of it, even your nude pics or your affair and messaging or apps you do not want a kid opening all have intrinsic value to yours, theirs, mine and every other Government from here to Israel to Saudi Arabia to Russia to South America and even to war torn African Dictator's Intelligence services.

Blackmail and coercion to name just a few of the thousand uses all of this type of data have to the Alphabet agencies of the world.

Example: The Ashley Madison leaks will aid in China's efforts to tie in and narrow down and find American Assets, ie, people, networks and the spies from America and her ever & rightly dwindling allies behind them that they gained from the OPM hacked data.

Closed source encryption... First sign something is aloof.

Now maybe it is not this, maybe the Dev. closed sourced it and has your data as his #1 concern and money as his goal. Which is possible, completely possible.

This begs the question then: How susceptible is his code to hacking, interception or confiscation and/or him to blackmail or payoff?

But whatever why split hairs... There is always the below:

Unless the Dev responds make this topic stay bumped as often and of course within all XDA guidelines and rules so others know there are issues like this and no DEV response.

This shall and will sooner rather than later cause his "Pro" sales to spiral and then they will be forced to respond. Also Google is an excellent tool as is dorking it to find every little nook and cranny of every .co.* and .com, .org, .biz, etc.. that this dev may have or is promoting this app and his others.

Lastly, if none of what I have said here gets them to reply? I think that is in and of an answer.