For some reason my browser (I've tried several) is not setting cookies even though a valid set-cookie response is being returned by the server when the GET call is made via Ajax using the fetch api to make the request
If I make the identical GET call via just putting the URL in the browser, the (identical) set-cookie response headers are respected by the browser and the cookies are saved.
I've inspected the request and response headers via LiveHeaders and the Chrome network inspector and there is no difference.
EDIT: To clarify, this is NOT a problem with ajax sending cookies to the server. It is a problem where the cookies are not saved by the browser at all when a response comes back with valid set-cookies headers (which according to documentation should be respected whether ajax or not).