I tried teleporting my mimic to me using /tp @e[type=probablychests:normal_chest_mimic_pet] @s and every other variant of tamed mimics, but no entity was found, I assume that means its dead, but no death message was displayed. This happened at sea so I assume there is either no death message at all, or there is a glitch where pet mimics may disappear at sea. It also was seen swimming away from me rather than toward me after my boat was broken.

If it is not loaded it can not be teleported, this is a base minecraft mechanic. It is just in a unloaded chunk and not a bug. and The mimic swimming bug is already a issue. please check other issues before posting.