I have a root - non-root link configuration working in a big shopping mall. There is one root and a couple of non-roots. I have configured one link SSID for the 5GHz band and two SSID for the 2.4GHz clients. Also all SSIDs have different VLANs configured.
Everything works just fine most of the time, but occasionally data traffic just stops: the 5GHz seems to be associated, but data won't go through - not even ping. SNR values are over 30dB, so it shouldn't be a signal strenght based problem. After rebooting the AP, the link starts to work again.
I've checked the area with Cisco Spectrum Expert and haven't found any 5GHz interference. IOS version for the APs: c1250-k9w7-tar.124-10b.JDA3
Config files attached.
There are two newer versions of IOS for the 1252. Have you tested with those? It sounds like a bug to me since your signal quality is good and cisco devices usually play nice together.