Boat sank into the sand

Boat was on the edge of a water stream above sealevel.  I dug 4 blocks out under the boat and the boat sank down 2 levels, and disappeared into the sand.  Then I dug out 4 blocks of sand to uncover the boat to take this picture.

 Perhaps related to https://bugs.mojang.com/browse/MCPE-32489, but that was fixed already.