HP Prime "Cannot Find Solution" when solving two equations

[DGRCarter]

I am trying to solve only two equations using the Solve App and it fails at every attempt. I just updated to latest firmware 20181016. The equations are super simple algebra:
S=(P*L*C)/I
I=pie/64*(D^4-E^4)

I made sure all the variables are in the system already. It will solve them individual, but not both at the same time. I tried this on my sons HP Prime with firmware: 20170710 and it worked two times, then stopped as well with the "Cannot Find Solution".

I also tried it on the emulator on my windows PC without any luck. Same issue.

Do I have a setting that is off or set incorrectly?
Any help would be greatly appreciated.

Thanks,
Geoff