Well, not all of your code is here, so its hard to tell, but if you mean to return the hash as a reference you need a return \%filters;, if not you need to do %hash = Module::method(); since you will be returning as a list. But more importantly, are you sure there is any data in the hash at the end? Use some print statements or even better change return %filters to:

use Data::Dumper;
print STDERR Dumper(\%filters);
return %filters;
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To make sure you actually have data!