Exocraft Beta sometimes after collecting crystal nodes, they appear under craft spinning, just a visual glitch, is fixed after a refresh. Also, on a couple different occasions I have been inside of the mobs with no warning, meaning they didn't appear on the mini map, and my shield did not go up, so I recieve heavy damage just out of no where, perhaps they respawned ontop of me after someone else had killed them, but there is a delay from the game.
One more thing, people were talking about lag in the game and freezing before the mobs, the only time I noticed this was if I had another browser open or another tab opened.