Cannot destroy end crystal on survival. Tried removing BEI mod and it works fine. Tried melee and range attack and explosions with no luck. Reset Island multiple times still crystals are indestructible .

Never mind this is an issue with Valkyrien Skies mod. To temporary solve the issue I ran the command below. (Need to Open to LAN on single player)

/execute as @e[type=minecraft:end_crystal] run data modify entity @s Invulnerable set value false