What’s the configuration of you CORS settings in the FME Flow UI?

As ​@hkingsbury mentioned, its all to do with your CORS settings and you need to add access-control-allow-origin . It is not in FME Flow's CORS settings by default and sometime it gets used, so is often something you need to add.

​@todd_davis ​@hkingsbury I’ve explicitly added them, at least I think I did? I also started with the default and started adding things to no luck.