I'm playing the mod on minecraft 1.21.1 with the latest version of the mod (1.1.7) on a server. For some reason the gliders can't be enchanted with mending and ubreaking while players are in survival, with only being possible after I changed the gamemode to creative.

This is due to not having tags.

data > minecraft > tags > item > enchantable > durability.json
&
data > vc_gliders > tags > item > enchantable > glider.json

both the minecraft file and the glider file should be something like:

{
  "values": [
    "#curios:cape"
  ]
}

I used the cape tag cause the #curios:glider tag didn't seem to be showing up in JEI/MEI, which I have no idea why that is.