It would seem to me, that OnCellAttach() is partly broken, when it involves disabled references and a simultaneous cell reset.

To be more specific, if you have a disabled reference in a cell that is due to reset, and you either fast travel to it or enter it directly from an interior, OnCellAttach() does not seem to work reliably, or fully as expected, for such a reference.

I previously brought up one aspect of this here: http://www.gamesas.com/topic/1420749-rare-but-odd-papyrus-quirk/. That didn't get much attention or interest, but I am not surprised, as the circumstances are a bit specific.

However, here is another seemingly related minor bug, that is easily demonstrated in vanilla Skyrim:
- Locate yourself outside Honningbrew Meadery
- Go to the nirnroot under the North-bound bridge to your NE. Hear it do the the looped nirnroot sound.
- Pick up the nirnroot.
- Enter Honningbrew Meadery.
- Wait until the exterior resets. (Use the console or a small plugin to speed up the respawn cycle.)
- Exit Honningbrew Meadery and return to the previously disabled and now reset nirnroot.
- Listen for the nirnroot sound - you won't hear it. (It will start if the cell is attached a second time)

So, it seems, that under these circumstances, the sound loop included with the reference fails to start running.
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A related question: does anyone know of a script function, that can force such a failed sound effect to start running?