Faild Request Tracing response buffer always "%1F%8B%08" with custom content trace

I am trying to specify Custom content to trace with Failed Request Tracing (FRT). I'm using "/ver1.0/sdk/java/*" as the Custom content value. The requests that are traced are the correct ones, but I always get a GENERAL_RESPONSE_ENTITY_BUFFER value ofBuffer="%1F%8B%08". If I trace "All content (*)", then I get the expected response data in GENERAL_RESPONSE_ENTITY_BUFFER. Our site is very busy, and I need to minimize the amount of trace files generated. This seems like a bug in FRT. I'm not reaching the maxLogFileSizeKB limit because these trace files are around 250KB, and I have been seeing trace files bigger than 400KB.

Any ideas on how I can get the correct response buffer in the trace files?

Thanks,

David