The unifi.proxy is moving to unsupported and then supported again. I can see this in the log file...
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=04:18:d6:20:93:21].[rssi>10&rssi<=15].rssi",,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=04:18:d6:80:c8:57].[rssi>15&rssi<=25].rssi",,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=04:18:d6:20:93:21].[rssi>15&rssi<=25].rssi",,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=04:18:d6:80:c8:57].[rssi>25&rssi<=40].rssi",,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=04:18:d6:20:93:21].[rssi>25&rssi<=40].rssi",,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=04:18:d6:80:c8:57].[rssi>40].rssi",,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=04:18:d6:20:93:21].[rssi>40].rssi",,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[sum,uap,default,"vap_table.rx_errors",57444e382ed0e7778ae1bd72,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[sum,uap,default,"vap_table.tx_errors",5404a444d0f9054c70518ec8,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[sum,uap,default,"vap_table.tx_errors",5404a444d0f9054c70518ec6,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[sum,uap,default,"vap_table.tx_errors",5404a444d0f9054c70518eca,0]" became not supported: Unsupported item key.
1542:20160916:134826.498 item "127.0.0.1:unifi.proxy[sum,uap,default,"vap_table.tx_errors",54a2d0c6d0f983b6dee0443f,0]" became not supported: Unsupported item key.
1544:20160916:134853.130 item "127.0.0.1:unifi.proxy[sum,uap,default,state,,0]" became supported
1542:20160916:134857.563 item "127.0.0.1:unifi.proxy[sum,uap,default,"stat.tx_dropped",,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[sum,uap,default,"vap_table.rx_errors",,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[sum,uap,default,adopted]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[sum,uap,default,guest-num_sta]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[sum,uap,default,isolated]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[sum,uap,default,locating]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[sum,uap,default,num_sta,,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[sum,uap,default,rx_bytes,,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=24:a4:3c:02:e4:c3].[rssi<10].rssi",,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=24:a4:3c:02:e4:80].[rssi<10].rssi",,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=24:a4:3c:b0:4c:b0].[rssi<10].rssi",,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=24:a4:3c:02:e4:c3].[rssi<20].rssi",,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=24:a4:3c:02:e4:80].[rssi<20].rssi",,0]" became supported
1542:20160916:134857.564 item "127.0.0.1:unifi.proxy[pcount,user,default,"[ap_mac=24:a4:3c:b0:4c:b0].[rssi<20].rssi",,0]" became supported
root@zabbix:~# less /etc/zabbix/zabbix_agentd.conf | grep UnsafeUserParameters
### Option: UnsafeUserParameters
UnsafeUserParameters=1