It has just happened a couple minutes ago ... the mobs vanished for about 10 seconds here are the exact co-ords and the server time so it can be checked ...
Server time 2070 October 28 17:33:28
Current location: Lat: 50.99°N, Lon: 98.04°E, Altitude: 300 m
I hope this helps narrow the bug down for you ...gl
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Again :
Server time: 2070 October 28 17:42:29
Current location: Lat: 50.88°N, Lon: 98.17°E, Altitude: 307 m
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Again :
Server time: 2070 October 28 17:58:37
Current location: Lat: 50.65°N, Lon: 98.04°E, Altitude: 284 m