First of all, good call in doing the My Domain update — you’ll be in a much better place after this is all settled. 

If you copy the full URL for the popup and paste it into a text editor, you should be able to see a “redirect_uri” URL Parameter, can you paste that piece of it here? 

Also, can you grant login access to Skuid Support? 

Thanks for the response! I included the entire URL and bolded the redirect URI parameter below: https://thebroadcenter.my.salesforce.com/services/oauth2/authorize?client_id=3MVG9CVKiXR7Ri5qryWurzAUob859MdLYBaVI_wLqOT7OMoV3GZuE1DfLjO6XPh2QAoeWbRwy1niTlWZkhGl.&response_type=code&redirect_uri=https%3A%2F%2Fthebroadcenter--skuid.visualforce.com%2Fapex%2Fskuid__oauthcallback&state=%7B%22client_id%22%3A%223MVG9CVKiXR7Ri5qryWurzAUob859MdLYBaVI_wLqOT7OMoV3GZuE1DfLjO6XPh2QAoeWbRwy1niTlWZkhGl.%22%2C%22network%22%3A%22TBC_DDS%22%2C%22display%22%3A%22popup%22%2C%22callback%22%3A%22_hellojs_3s32ekbl%22%2C%22state%22%3A%22%22%2C%22redirect_uri%22%3A%22https%3A%2F%2Fthebroadcenter--skuid.visualforce.com%2Fapex%2Fskuid__oauthcallback%22%2C%22scope%22%3A%22basic%2Cfull%22%2C%22oauth%22%3A%7B%22version%22%3A2%2C%22auth%22%3A%22https%3A%2F%2Fthebroadcenter.my.salesforce.com%2Fservices%2Foauth2%2Fauthorize%22%2C%22grant%22%3A%22https%3A%2F%2Fthebroadcenter.my.salesforce.com%2Fservices%2Foauth2%2Ftoken%22%2C%22response_type%22%3A%22code%22%7D%2C%22oauth_proxy%22%3A%22https%3A%2F%2Fthebroadcenter--skuid.visualforce.com%2Fapex%2Fskuid__oauthproxy%22%7D&scope=full I've also granted login access, let me know if you need anything else.

Eulogio, can you confirm that you have added this Callback URL to the list of Callback URLs in your Connected App?

https://thebroadcenter–skuid.visualforce.com/apex/skuid__oauthcallback

That did it Zach, thank you so much!!

I originally had this URL which was working before the My Domain update: https://thebroadcenter–skuid.visualforce.com/apex/oauthcallback

Just leaving this here in case anyone else runs into similar issues.