I actually do have cordova-plugin-file installed as well sorry. I was only listing the plugins I thought were necessary.
In reality I have a few plugins installed:
In my cordova config.xml I have these tags:
<plugin name="cordova-plugin-whitelist" spec="1" />
<plugin name="cordova-plugin-game-center" spec="1" />
<plugin name="cordova-plugin-inapppurchase" spec="1" />
Most of the time I don't seem to need to add plugins to this config file otherwise.
To build I just do:
And then I open via Xcode and compile etc.
I've tested my setup with the exact same .capx and done exports with wkwebview enabled and disabled. When it's enabled I get the AJAX failure, when it's disabled the AJAX works fine.