on java thee is a bug for 18w48a to 18w50a when you have a command block on repeating and always on if that block gets unloaded it stops working when it gets loaded again
MC-141038
repeating commands
Resolved
Duplicate
0
(Unassigned)
Unconfirmed
Minecraft 18w48a, Minecraft 18w48b, Minecraft 18w49a, Minecraft 18w50a
Retrieved
Sounds like MC-140985