Hi Starr,
There must be an issue on your sim, maybe you could ask the landlord to restart it ?
Also, kittens are small, they do hide or whatever at times, but will 'jump' at their home
position once they fall asleep, so every 4 hours. (Adults every 8 hours).
KittyCatS team ALWAYS retrieve lost kitties, so don't give up, file another ticket and
they'll send your cat back to you.
What could be good in the future is you reduce the range of your cat to the minimum (3 meters)
(left click, animation, set range, custom) or even turn her walk / run off for now until she gets
older & bigger, or turn her walk / run on only when you are with her (left click, animation, deselect walk/run),
that would allow you to still enjoy her moving around when you are there and might avoid the poofing problem.
Nen