I am using make.com to add events to LinkedIn.

I would like to include a background image to the event, either when creating the event or as an update, but make.com is giving me a 400 error if I include an image. I've tried using what I retrieve from a previously created event, which gives me "urn:" followed by an identifier, but that leads to the 400 error.

Is there a way using an api call to use that urn identifier, or any other way, to add the event background image?