The History server supports being consumed via a proxy using the spark.ui.proxyBase property. Despite it works fine if you access the proxy using a link which ends with "/", it doesn't show any application if the URL accessed doesn't end with "/", eg. if you access SHS using https://yourproxy.whatever:1234/path/to/historyserver/ it works fine, but it you access it using https://yourproxy.whatever:1234/path/to/historyserver no application is shown.
The cause of this is that the call to the REST API to get the list of the application is a relative path call. So in the second case, instead of performing a GET to https://yourproxy.whatever:1234/path/to/historyserver/api/v1/applications, it performs a call to https://yourproxy.whatever:1234/path/to/api/v1/applications.