Hi!
Just for me to understand: This is a second AP on the same radio0 device, right?
I have seen the same errors (hostapd: handle_probe_req: send failed) when I tried to run multiple SSIDs on the same interface. There is a solution - DRCS, but it seems not to be working with the current version of the mwifiex firmware. We are working on getting newer firmware with multi-SSID and DRCS support.
Tomas