This issue was solved by the realization of where the wix-fetch call was coming from. I was hitting a local server that I have running on a raspberry pi. Since it has a self-assigned certificate, by default, it is flagged by browsers and servers when trying to connect as being a security risk.
The resolution was hitting my API on my AWS instance which deals and issues CA certificates and therefore was valid and fetch now resolves successfully from the back end.
Moral of the story: Backend fetch calls must be made to non self-assigned certificate endpoints otherwise it will time out.