I had the same issue. I was able to fix it by editing the config file via putty from my computer (using ethernet for the connection of course). Whenever I typed my wifi-password in, it was gone the very next moment, so was my ssid. I was able to fix this by doing the following:

connect your Pi with your desktop-computer via ethernet edit the config file manually by typing in your ssid, your wifi password and setting wifi.enabled=1 remember 2 things: delete the ";" infront of those lines, thats the reason why it didnt work for me the first time after you get an recalbox update, the config file is NOT getting updated automatically (as far as I can say), thats the reason why it didnt work for me the second time 🙂

I hope I could help.