Do the following for a request that works and one that doesn't, then compare the results.

{
   require Data::Dumper;
   local $Data::Dumper::Useqq = 1;
   print(STDERR Data::Dumper::Dumper($request));
}
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I suspect you might need to encode $request. If so, and if you have warnings on as you should, you should be getting "Wide character in print" with the code you posted.