This could be a few different things...and the description isn't complete so here's some things to check:
Are you on the same WLAN/channel - check the 2.4 and 5ghz connections/MAC addresses
Remove any encryption and put everything on an open wlan (temp)
Turn off one of the radios (only 5Ghz if anything in the mix is 2.4-only)
Turn off client isolation
Remove any ACLs
Can you connect to AV devices via something other than their GUI (can you ping, SSH, telnet, etc?)
things that will help narrow it down:
Version of ZoneFlex
Basic description of network config and topology
What client you are testing with (PC?)
Do you have client isolation enabled?
Did this ever work?
What kind of AV devices
Have you changed anything via CLI or "advanced" settings?
How is IP addressing provided? By what device?
Do the Av devices have any network diagnostics?