Can't add POI in Wailing Caves
 

Can't add a new POI to Wailing Caves (West):
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The following error(s) occured:

* The loc '-67.48, -51.70, -178.60' does not appear to fit into
this or any related zone.
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(Druhdak Shin`Ree, L15 ^^^ skeleton orc)

Any ideas? I'm absolutely sure that the location is correct - there's even another POI just a few steps from it.