Without even referring to how woke it was, the live Mulan was just boring. How are you supposed to relate to someone who was already a literal superhero and whose only problem was that she was being “held back" by the system? There's no hero's journey, no failures, no real dangers, no fault of her own. You're not invested in her character. You don't feel for challenges. Every fight scene and conflict felt contrived because you knew she was going to win.
In the end she even got to be friends with the enemy witch by helping her break free from the clutches of whatever patriarchy the bad guys had on her. If I had her superpowers I wouldn't be someone's resident witch — I'd be the leader of the tribe. I get to decide who we fight and why. Amateur.
Compare live Mulan's story to that of Neo from you-know-what. Mulan was already a mature character from the very start of the movie. Neo, on the other hand…
Even Neo, who everyone acknowledged to be the One from the start, had to:
1. screw up every which way during training,
2. get almost everyone at the Nebuchadnezzar killed,
3. get Morpheus captured,
4. have his ass handed to him when he tried to battle Smith,
5. die inside the Matrix,
6. have sentinels tearing the Nebuchadnezzar apart,
7. put everyone's lives in danger including Morpheus his mentor and Trinity his lover…
…before rising up again and realizing his powers as the One.
Anyway, live-action Mulan failed in large part because whoever wrote it didn't write a character you could sympathize with. Plus, it sent out a really shitty message that because you have the awesomeness in you, you don't need anyone telling you what to do, even if you're a literal soldier in what is essentially a war movie.