@Kasay Mardis If you truly suspect price point is not your problem, I would spruce the unit up a bit as the other poster mentioned but also Google real estate photographers in your area and hire one.
Some of the best money you will ever spend. They are very affordable and worth every penny. I have one I've hired several times, costs between $150-250 and got me great angles and lighting of every space, aerial drone photo and video etc. They can even have the drone indoors and doing a tour of the whole space and help someone be able to see the layout and what it's like to walk through it. Document the space once and use it in perpetuity unless there is a significant change to the unit or building.
I'm no marketing pro, but did you ever watch Mad Men? Remember when he says ads are based on one thing: happiness. It may sound silly to you, but people can be very visual and simple about this.. You want to help them imagine seeing themselves content and happy in the living space you're providing as much as possible. It really goes a long way to have thorough and well lit photography for this.
Good luck and good on you for opening yourself up to suggestions and improving!