Yes, that was discussed above, though it still doesn't really explain why the AP won't use 802.3at even when set manually to that mode. The MS510TXPP is part of Netgear's Smart Managed Pro series, and certainly should support power negotiation via LLDP-MED. I also investigated with Netgear, and the settings on the switch appear to be correct.
I can't entirely rule out an issue with the MS510TXPP firmware, but this seems to have started with a Ruckus firmware update. (I had the same experience as the OP.) Can Ruckus provide any further steps to investigate on the AP side? Is there a list of known compliant switches?