Can you both try connecting to wireless using the command line tool connmanctl. This will rule out (or implicate) the networking GUI.
To do so you’ll either need to temporarily connect Ethernet and run the command via an SSH session, or plug in a Keyboard and exit Kodi to log in at a local console session:
Once you’re logged into a command prompt the following demonstrates enabling wifi, scanning for networks and connecting to an authenticated network:
osmc@rpi2:~$ connmanctl
connmanctl> enable wifi
Enabled wifi
connmanctl> scan wifi
Scan completed for wifi
connmanctl> services
*AO Wired ethernet_b827ebd04564_cable
wifi_e894f6191023_hidden_managed_psk
VM420130-2G wifi_e894f6191023_564d1235f53035302d3247_managed_psk
connmanctl> agent on
Agent registered
connmanctl> connect wifi_e894f6191023_564d1235f53035302d3247_managed_psk
Agent RequestInput wifi_e894f6191023_564d1235f53035302d3247_managed_psk
Passphrase = [ Type=psk, Requirement=mandatory, Alternates=[ WPS ] ]
WPS = [ Type=wpspin, Requirement=alternate ]
Passphrase? xxxxxxxx
Connected wifi_e894f6191023_564d1235f53035302d3247_managed_psk
connmanctl> services
*AO Wired ethernet_b827ebd04564_cable
*AR VM420130-2G wifi_e894f6191023_564d1235f53035302d3247_managed_psk
wifi_e894f6191023_hidden_managed_psk
Let us know whether you are able to connect this way or not.
(BTW connmanctl has a very useful help command)