Linux

Java 1.8.0_2262 64bit

Lost 4 minecarts with hoppers on first minecart project. They all disappeared in minutes.

12 rail section with 1 powered rail on each end with stop blocks. cart bounces back and forth.

Left line of sight, but stayed with 10 blocks, come back, cart is gone, few minutes tops.

Lost 2 more when testing riding and hill climbing.

  #1,  I ran a few test runs, went 10 blocks away for more rails, came back, gone!

  #2,   I pickaxed cart and never left it, back to rail, dropped cart, pushed cart, disappeared in my hands, magic!