We are having a similar issue. Running ZD1200 and 3 R710s in a full El Capitan (10.11)/Yosemite environment (some Linux clients).
Symptom: A wifi connected client will experience connectivity loss to the default gateway (and of course the public internet as well) for roughly ~10 seconds; all applications/connections will automatically re-connect where applicable after this time. This does not involve a drop in connection to the wifi. At first, Ruckus tried to state that this was a GTK/PTK corruption issue involved with WPA2, which can only rectified by upgrading to Sierra (as you see, it has not solved your issue). Confirmed loss to default gateway by seeing ICMP drop.
After pushing back, we ended up putting a packet capture on the ports that each AP is connected to, and what I found was that at some point in time all return traffic fails to respond to the client's requests, which continue trying to retransmit un-ack'd packets; the requests fail to even reach the AP, proving the issue is on my network at first glance.
What is interesting is that this only occurs for wifi clients, not ethernet. Furthermore, our network is ridiculously simple in terms of design/configuration, so I truly believe there may still be an issue on Ruckus's end.
My current plan of action is to continue to isolate where the return traffic is not returning, and then work with my network vendor.
Please let me know if our symptom is similar to yours.
Edit: Also, what is the frequency of your issue? For us, it is anywhere from affecting multiple clients a day multiple times a day to no issues (or at least, no clients reporting issues to me) for a week or more.
Edit: We do not experience any major latency issues (500+ ms) prior to the drop