When switching to wkWebView in Cordova for iOS some plugins have the known issue that cookies won't be used properly in application because of apple restrictions.
While this issue could probably only get fixed by Apple in the first place, there is a simple workaround available to get it working: Once a dummy cookie is placed into the WKHTTPCookieStore manually, the syncronization gets triggered (started) and it won't bug you ever again.
document.addEventListener('deviceready', () => {
wkWebView.injectCookie('mydomain.com/mypath');
});
You have to replace "mydomain.com" with your domain name and "mypath" with your subpath. If the latter is empty than you don't need to provide it (just leave the trailing slash there to tell the plugin that you don't use any extra path).
Once you have injected a cookie all further (session) cookies are synced properly.
If you want you could also pass a success and and error handler. The success handler will be called if the cookie was injected properly, the error handler if not.