It's hard to give a really cut and dried answer without knowing all the details, but here are some tips based on my experience:
First the bad news: from the way your question is worded, it sounds like you built the app without validating first. What I mean by that is that you didn't go out to the musician market BEFORE you built it to make sure they would buy it. And the only way to be absolutely sure that they would buy it (someone telling you, "Yeah, I'd totally buy that." doesn't count) is to pre-sell the app for real actual money. The key is to do this market validation before building anything.
Now for the good news: even though your target market isn't showing much interest, it sounds like others are, so here's what you do: make a list of the folks who are interested and the industries they're from. Now research those industries and find the particular pain point that your app solves for. THIS is how you market the app. It probably means getting in touch with some of the people who have shown interest and asking them questions along the lines of, "What's the worst part about..." or "What do you hate most about..." and then listen to what they tell you. Tailor your solution to solve these pain points and you'll be surprised how receptive the market is.
The critical takeaway here is validation. When it comes to app development, there really is no substitute for market validation. A good place to start (if you haven't already done so) is with a Business Model Canvas (https://strategyzer.com/canvas). It'll really crystallize your thinking and give you a specific direction.
As for whether you should pivot to a new target industry, I can't think of a reason why not, especially if your app provides a unique solution for a different industry.
I'm happy to walk you through the validation process and/or the Business Model Canvas over the phone if you like. Hope this helps.
