It disables all forms of flight from other mods as your code blocks other mods code to work. Examples of this is shown in this reddit post:
https://www.reddit.com/r/feedthebeast/comments/84rcy8/magic_feather_disabling_all_other_forms_of/
this code here disable all other mods abilities flight abilities:
https://github.com/Ephys/minecraft-magic-feather/blob/master/src/main/java/be/ephys/magicfeather/ItemMagicFeather.java

That's definitely not intended, will fix!

thank you ephys :D

Hey, just a suggestion for how to make this work if you haven't come up with your own solution for it:

Why not give the player a "flight" potion effect when they both have the magic feather in their inventory and are in range of a beacon? Then, instead of stripping away their flight when they move out of range, you can just have the potion effect expire naturally.

Of course, if you already have your own solution, you can just disregard this suggestion.

Any luck with fixing this?

@ephys What’s your progress on the fix?

This mod looks amazing, but I don’t want to use it until this has been fixed, as it’s a pretty major bug.

It's been a year, it's dead Jim

Looks like it. That’s a shame, though.
I hope someone will fork this and take over the project. It’s such a nifty mod!

@ephys Sweet! When is the update being released, and will it be for 1.12.2?

(I'm back)

So as suspected it was caused by the slow-fall feature (you don't get fall damage until you hit the ground when stripped of flight)

I've reworked the code so that the mod will only strip you of creative flight once and only if it granted it first

Sweet! As soon as it’s released, I’m adding it to my modpack!

@Dimentive I'll be testing the changes I made for #4 after work, then I'll test the mod in an actual modpack before I release it. If everything goes smoothly it should be out in a few hours

And yes, 1.12.2 :) 1.15 soon™️

I genuinely, honest to god love you. I don’t believe in god, though, so that doesn’t hold much weight, but I still love you.

I thought this mod was abandoned forever, but then you show up out of nowhere and resurrect it like you’re a necromancer. Not even joking when I say I’ve been waiting for this. This is the perfectly balanced flight item. It’s a great mid-step between basic flight like the ring of the flying squid, jetpacks, and other simple flight items and full creative flight. I love this mod so much and hope it works as advertised! I’ll install it immediately.

It's under review by curse but should be available shortly :)

https://www.curseforge.com/minecraft/mc-mods/magic-feather/files/all

Edit: already approved

hearing that makes me super happy! Enjoy :)