I've experienced this issue as well in my "lab" (home) on ZD 1100's with firmware v. 9.10.0.218, with a single ZF7982 & a single R700. I don't know which AP I'm connected to when this occurs.
Your fix, of forgetting the network and reconnecting, is the only way I can get normal connectivity back again. I'm connected to the wireless network but have no Internet access, I'm unsure about availability of local resources. I've experienced this problem intermittently on iphones, ipad & Mac book air (2013), when either returning to the environment, waking from a "sleep" mode, and possibly in the case of the Mac book air after a reboot. It hasn't occurred enough that I can troubleshoot it effectively.
I'd be curious what version you'r running.
I did ask Ruckus about this last week and was told they didn't know of any issues with Apple devices.
Please post if you discover anything. My work environment has over 100 iphones and I don't want to upgrade until I can determine if this is going to be a problem at work.
Todd