This may be similar to the other failing elytra tickets. If you equip an elytra while in creative mode (right click while holding), and then change gamemodes by using ./gamemode survival the elytra will not be able to be activated. .I haven't done vigorous testing into what fixes it, but re logging definitely does, but I can if this ticket isn't marked as duplicate.
Comments 3
No, I tried this in an entirely new world, where the only other thing i did was ./fill to clear an area. It also occurs across dimensions but I saw the ticket for that so it's different(but possibly related).
Have you been teleporting to other chunks/changing dimensions?