So I just installed the latest version of Java 7(v51) on matrix version 4.14.1 and now my asset map is broken. I think it's something to do with this:
https://blogs.oracle.com/java-platform-group/entry/new_security_requirements_for_rias
I don't know if this is fixed in newer versions of matrix (anyone able to clarify?), but I'd recommend against installing the latest version of java if you want a working asset map.
PC or Mac?
PC
the security features are present in the latest Mac version as well though, so it'll probably be affected as well
Did a little more poking around and if you add each matrix site you use (ie. http://mysite.com/_admin/) to the exception list it'll work - https://blogs.oracle.com/java-platform-group/entry/upcoming_exception_site_list_in
I guess just another reason to upgrade to get the Modern Asset Map.
oh nice, didn't realise that'd been released. A welcome change.