I'm sending data w/ headers to my server from the client (https client on my heroku domain) without any issue on Chrome mobile but iOS safari won't POST the data.

Below javascript sits on the client side and pulls data from the geolocation API in the users mobile browser (after asking for permission). Both Chrome mobile and iOS Safari get to the step of asking the user for geolocation approval, but then iOS safari sends another 'GET' to the endpoint instead of a 'POST' like Chrome mobile.

const status = "Y";
const guest = cookies.guest_id;
const data = { status, guest };

const options = {
    method: 'POST',
    headers: {
        'Content-type': 'application/json'
    },
    body: JSON.stringify(data)
};
fetch(`/events/${eventID}/prompt`, options) // my endpoint

My understanding is fetch() is fully supported by iOS mobile, so why isn't it executing as expected?