I have noticed (bug? feature?) of skyblock.org server - time glitches, when events go back for 1-2 seconds. During one of such glitches I have lost a sand block (which has been mined and I was about to pick it up when another glitch struck). Is it a known problem? Of course I can't prove the above (that I lost an item during such an incident), but time skipping back happens quite often). Thanks.
This is actually called lagg. This occurs when many people are on, or the server just cant keep up. So it "laggs" back. You probably lost your sand block from CLAG, which is a plugin that clears entities (items) off the ground after a certain period of time. I hope that helped
It surely explained why it happens, but it looks like losing items that were momentarily on the ground (for less than 5 seconds) is an inevitable event. Thanks.