You may have some kind of strange filesystem problem — how are your filenames flipping between /play_ground/cov/... and /apollo_dev/apollo_tests/play_ground/cov/...?

You have broken something or you are tickling a bug in Devel::Cover. The first suggestion I have is to remove all of the options and set PERL5OPT to exactly "-MDevel::Cover". You may be specifying options such that Devel::Cover ends up not actually including anything and producing an invalid database.

And until you get this sorted out, remember to delete the coverage database after each change, so we do not have an old coverage database hanging around to give us bad data.