I noticed a strange caution message when looking at downloaded resources using Google chrome inspector (F12):
Caution provisional headers a
"Caution: provisional headers are shown" message can be shown when website hosted on HTTPS invokes a calls to WebApi hosted on HTTP. You can check all if all your Api's are HTTPS. Browser prevents to do a call to insecure resource. You can see similar message in your code when use FETCH API to domain with HTTP.
Mixed Content: The page at 'https://website.com' was loaded over HTTPS, but requested an insecure resource 'http://webapi.com'. This request has been blocked; the content must be served over HTTPS.