[MC-143641] Some naturally spawned shulkers do not shoot missiles

Some naturally spawned shulkers do not shoot missiles

Seed: -1616642514759128771
/execute in minecraft:the_end run tp @s -218.99 61.00 -1228.37 -273.90 -8.40
/gamemode survival

→ The shulkers did not shoot missiles and the missiles explode inside the sulker
There are also a warning on the game output

 Keeping entity minecraft:shulker that already exists with UUID 5a1e0699-a25e-4a07-bab3-4480fd8c6ac2