Hey Fabiano,Thanks for reporting this. This is a bug and will be fixed in the next version.In the meantime, as a workaround, could you try hosting the capabilities file on your own server. Loading of the tiles do not require the crossdomain file(hence no proxy), so it should just then work fine.If you still want to go through the proxy, you can adjust tile url(GetTile operation) so that it contains the proxyURL. Something like:
<ows:Operation name="GetTile">
<ows:DCP>
<ows:HTTP>
<ows:Get xlink:href="YourProxyURL?http://v2.suite.opengeo.org/geoserver/gwc/service/wmts?">
<ows:Constraint name="GetEncoding">
<ows:AllowedValues>
<ows:Value>KVP</ows:Value>
</ows:AllowedValues>
</ows:Constraint>
</ows:Get>
</ows:HTTP>
</ows:DCP>
</ows:Operation>
Hope that helps.