My color guard unit cannot sign up for the Season 2 preview (Aug. 17) despite having a show application remaining. I even withdrew my application from an event, and I was still not allowed to join. I've had similar issues with my other units.

have you already been accepted to 5 shows?

Yes, which would explain the rejection, but why do I still have show applications remaining?

Because you can apply to 7 shows per week. The number at the top there only shows the formula: 7 - [number of shows you've applied to]. In the off chance a show would need to be deleted, that number would still be valuable.