For the last 45 minutes I have been attacked by invisible mobs.
Current location: New Urengoy [Q], Lat: 58.42°N, Lon: 98.90°E, Altitude: 251 m
Server time: 2069 February 09 11:24:02
By the damage - these are the normal NU mob (wolf, slugroach).
The creatures attacking me are not shown in my view of the game and not shown on the radar (no red dots).
Note: this is resolved by a relog
In addition - the stones also disappeared during the above issue.