I'm having the same bug! Whenever a tenant dies, I can no longer fill the vacancy, but also can't evict them since they're no longer showing up. My sim had an in-law cottage and when her dad died of old age I couldn't do anything about the vacancy and it rendered the cottage useless.
Something I noticed as a quick workaround: I went into manage worlds and went to the newly "vacant" (though not showing as vacant) unit, and was able to "Create a New Household to Move In". I then moved them into the unit and then was able to evict them from manage worlds. This freed up the unit and I could now fill the vacancy as the property owner!
