I use it once but has bugs – Minimoog Model D Synthesizer Review

So I download this app,at first it’s great,but the second time I use it,I really don’t hear anything.can you fix this moog music? UPDATE: Sorry, this was my 12yo son and he’s been watching videos of people reviewing various things. We closed a bunch of apps and restarted this one and everything was fine :)
Review by Robertsca on Minimoog Model D Synthesizer.