I have an LG Stylo 2 MS550 running the stock android 7 for Metro PCS.
My bootloader is unlocked, I'm rooted, and the recovery partition is flashed with TWRP.
I originally flashed a custom ROM that upgraded my phone to 7.1.2.
I rooted the phone and copied a custom boot animation to the media folder.
The animation played just fine.
I had to reflash the stock ROM as the custom ROM wouldn't take my carrier's APN settings.
Anyway, the stock ROM won't play my custom boot animation.
I've tried tinkering with the desc.txt file.
I compressed it with winrar in store mode.