Sorry, but as you probably know, these "one man projects" are hard to maintain. I'm working full time on another company right now and it's not an easy task to find time for this.
About you problem. Frankly, I have more than 2K (2,041) downloads right now and no one has asked me about this problem before. I've tested this app everywhere for a year (yesterday in two different computers) and it just works. It's based on 4.22 Unreal and the only custom stuff I've coded is a little chunk of C++ for the Synth generator. The rest is pure unreal. Packed as always.
I'm afraid that the error could be a combination of your exact system and my app, something I could not resolve because I don't have those exact variables here. Sorry again about that. I really think that the refund is a great option in these cases.