I wonder if it's related to having a bareword (my_sort) while strict subs is in use? I changed your code slightly: 
@data = map { join '/', @$_ } sort {my_sort} @data;

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... and got this error: 
Bareword "my_sort" not allowed while "strict subs" in use

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In reply to Re: Sorting, recursion, and tail-call optimizations by kwaping
in thread Sorting, recursion, and tail-call optimizations by Limbic~Region

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