Unable to deobfuscate GWT stacktrace

After further investigation it seems that the new GWT compiler option -XenableClosureCompiler that we were using generates code that is not outputting stack traces that uses the symbol maps generated by the compiler. After removing that option, the stack traces can be deobfuscated successfully.

As a side note, the compiler and GWT module options required to enabled stack trace deobfuscation (the ones described in my question and removing the closure compiler option) make our final js files twice as big as before.