When you are crafting firework rocket with modifications, the modifications don't loaded.
like: Firework Star(Lime, Green, Creeper Shaped) + Paper + Gunpowder = Firework Rocket(Lime)
Linked issues
is duplicated by 7
MCPE-42329
After you make a firework star with like dye and glowstone when crafting into a rocket it turns into a normal small shaped firework all the effects disappear.
Resolved
MCPE-44112
You can craft Creeper-shaped firework stars but impossible to craft Creeper-shaped firework rocket
Resolved
MCPE-44593
Can’t craft custom fireworks MCPE
Resolved
MCPE-45541
[Resolved] Crafting firework rockets with firework stars doesn't display the 5 types for firework explosions
Resolved
MCPE-45988
Fireworks
Resolved
2 more links
Fixed in beta 1.12.0.6, I think...?