Unable to access internal web application through Azure Application Proxy

Question

We have an on-premises NavOne application, whose HTTP URL works fine internally. However, when it is exposed to the internet through an Azure Application Proxy, its HTTPS URL is not accessible over the internet. It fails with a CORS error (seen in developer tools) followed by net::ERR_FAILED 200 (OK). After authenticating, the page shows a blank page and also "Getting ready..." and it circles forever.

1. While on-premises, the HTTP URL (it has a non-standard port, if that helps) works fine and the traffic goes through a Citrix VPX Load Balancer.
2. Also, when I try accessing the HTTP URL using each server's name (bypassing the Citrix VPX LB) instead of the DNS hostname, it works for all servers. So, it is not a server-specific issue either.
3. The problem happens while trying to access the HTTPS URL (pure HTTPS, has no port element unlike HTTP above) over the internet through the Azure Application Proxy.
4. Tried enabling and disabling translation of URLs in headers and application body; did not work.

In my case, after keying in the credentials and 2-factor authentication, the application challenges for credentials, after which, it shows the blank page. I am wondering if my case matches option 5 in the below article because I do see redirection happening to login.microsoftonline.com.

https://learn.microsoft.com/en-us/azure/active-directory/app-proxy/application-proxy-understand-cors-issues

Can someone please guide me as to what could resolve the problem?