The issue is caused by the configuration line below in the web.config file of a .NET Core Application/Website.
<add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
The above line prevents all HTML files to open on the whole site not only the Web Statistics. As a workaround you would add the following lines to the web.config file located at the following path with a Domain hosted with Adaptive Web Hosting:
\.plesk\statistics\yourdomain.com\webstat
<handlers>
<remove name="aspNetCore" />
</handlers>
