It
MAY be due to the fact WPA Enterprise configuration settings in OpenWrt have changed in the last versions.
These changes are not released yet, so you would need to use the development version to try this.
However, I am not 100% this is the problem here.
So further debugging is needed on your end, you can try to generate the configuration through the OpenWrt Luci Web Interface first and see if you get it working, then compare the config with the one generated by OpenWISP to see if they're different (probably).
I hope this helps.
Federico