It seems that breaking the rails, stops the cart from disappearing. Strange...
Except for then the cart cannot be bumped onto a powered rail (which should not happen because there are nobody but me around to bump it and then I would just find it at the end of the rail, which I dont) why would breaking the tracks stop the cart from disapearing?
I do not have any Golems or other mobs running around in the mine.
I will try breaking the rails on both sides next time I am down there, but that will be a few days to go.
Crash report.
Minecart sitting on powered down track. The powered section it two blocks long. To the left and right there are powered up sections, so when I need to go I just jump in and push it onto one of the powered up sections.
Happened again. Took the train up to my 'hold'. Got of and logged out. When I logged in this morning, the cart was gone. Follow the track all the way to where the cart should have ended up if it was bumped, no cart to be found.
I upgraded to v1.51 yesterday, but this happend after the upgrade.
I include a screenshot of the endpoint where the cart was parked.