What are some things female writers fail at when writing male narrators?

This has nothing to do with gender. People are different. A writer must write many characters who are different than themselves. And why just female writers? Men write women narrators as well. It's up to the writer's individual skill and talent to create a convincing narrator, which is difficult no matter who that character.

The same things that all writers tend to fail at - they make characters into little copies of themselves. You'll find a heck of a lot of adult male characters in online writing who sound and think pretty much like teen girls.

Capturing male emotions. Men and women tend to think differently, so you can often be aware of the narrator(s) gender.

A pet peeve of mine is when female authors have a male character internally panicking and overthinking (Usually over a crush they have yet to talk to.) shamelessly on levels that sane women don't even reach.

My biggest problem is when a male character feels to feminine to the point it makes him a weak character.