Unloaded Merms do not teleport home.

If a merm that is not hired and has a home is unloaded, it will remain there until loaded again, and must be manually loaded by staying near it or by killing it in order for it to successfully return home.

The same as this bug report, but apparently repeat bug reports are how you get things fixed.

Suggested fix:

If a merm has a home, and is unloaded, teleport it back to its home.

Note:

May also affect pigmen, bunnies and catcoons. Less potentially impactful as they have a habit of picking fights with random spiders and thus tend to die a lot of the time, as well as them being less incentivized as hires and often from naturally spawned buildings.