I'm also getting this issue. How do I fix it?

Hmmm that's weird. My test case was showing 06:25 and that's why I was getting the one failed case. Anyway, I manually changed it and my solution worked against random tests

Are you sure it's not your own code that is saying 06:25?
And are you sure that you aren't mixing up logs from different test cases?
In the sample tests there is this:

Test.assert_equals(what_is_the_time("06:35"), "05:25", "didn't work for '06:35'")

There is an error in the test cases. If you in fact look at an analogue clock, the mirror of 06:35 would in fact be 05:25, not 06:25 as given in the test case for this kata

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problem should've been more specific with less giveaways