As you say it works for the first part in live, then you might not have a catch handler to the promise returned by a then method, which therefore is without handler for when the promise rejects.
You say that you can’t post code for security reasons, that is fine. The only way that somebody can help you though is to be able to look at your used code.
The only option you have really is to allow a Wix Admin/Mod from this forum to view your Wix Editor to see it.
You can do that by posting up your Wix Editor URL here and it is ONLY Wix employees who have the permissions to do this for security and safety reasons etc.
Corvid Masters and Forum Ninjas are just like yourself and can’t open editors apart from our own.