IIS 7 and Above
.well-known directory served only from one host-header iis8.5
Re: .well-known directory served only from one host-header iis8.5
Jan 10, 2019 07:44 AM|Jalpa Panchal|LINK
According to your description i created a demo asp site and create virtual directory in,it work work well with dynamic binding:
In my opinion firstly you could remove site from IIS and try to host again and create virtual directory.
Check that can you access site with second hostname without error.