Geoserver tiled layers preview incorrectly points to http://127.0.0.1:8080/geoserver/gwc/... even though "Proxy Base URL" is set correctly. The expected behaviour would be that the previews point to addresses prefixed by "Proxy Base Url" instead.
If the wrong prefix is replaced by hand on the browser address bar, the preview works. The problem seems to be only with the links displayed on the tiled layers preview.
The regular non-tiled layer previews work as expected.
This is the code to create the WMS demo page links in v2.9 (which works):
This is the code to generate the GWC (tiled) demo page links for v2.9 (which does not quite work):
It seems that the problem is in the GWC demo page generation which does not pull the getGeoServer().getGlobal().getSettings().getProxyBaseUrl() property.
The "actions" links have the same problem: