Chests turn invisible

Double chests turn invisible, lose their inventory and turn into single chests.

When I leave my world I expect my stuff in double chests to be safe.

When I entered my world all my double chests reverted to single chests, turned invisible and their contents were lost.

Sadly I cannot reliably reproduce this...

Sorry if this has all ready been reported but my kindle won't load most page's
in the bug tracker. (Could that be fixed?)