Trace headers missing from browser requests

[austere pivot]

I'm at a loss here. I can see trace headers (sentry-trace and baggage) going to my main site origin on the initial load but they're missing for any request that happens in the browser after that (no matter the origin).

For instance, say I have an image and the src is my service:

<img src="example.com/image.jpg">
<img src="api.example.com/image.jpg">

If I look at the requests in the browser when the page loads, the sentry headers are missing so I don't have any distributed trace info for those requests.

I also tried setting tracePropagationTargets in my Sentry config but nothing works. 😞

How would I go about fixing this?

[verbal lynx]

the headers are added to XHR and fetch requests. From what remember the images from <img src=...> do not use this kind if requests.
i made a test and if I send a manual fetch request to the same URL in my <img src="example.com/image.jpg"> line, this fetch request gets the baggage header with the trace propagation

[austere pivot]

Gotcha. So it's just not a thing unless you manually fetch?