I am experiencing the same issue, running an 1.11 and older version of Minecraft through Minecraft Realms. It's a quite large jungle, spanning 1000x1000 blocks To my knowledge even some parts of it has been ungenerated previous to 1.12 which should have spawned them. Is there spawnrate very low or should I keep looking?
I can confirm a much similar occurrence happening with mostly any block destroyed (ie. harvested, picked, chopped and so..).
Confirmed for 1.8,
Attatched screenshot.
I found a similar problem which earlier has been confirmed to be duplication of this bug. Riding a horse facing with my back towards a wall and then jumping will cause suffocation to the player. This is confirmed for 1.8-pre*.
Confirmed for 1.8-pre2 & 1.8-pre3.
Confirmed for 14w29b.
Confirmed for 14w21b.
Video of reproduction: http://youtu.be/mv2Roy_trw8
Reading through the logs as the upload takes place leaves me with this error message:
<log4j:Message><![CDATA[[STDERR]: java.lang.RuntimeException: file name 'world/datapacks/bac_advancements/data/blazeandcave/advancements/adventure/the_great_blocky_reef.json' is too long ( > 100 bytes)]]></log4j:Message> </log4j:Event>
This leaves me to believe there is a build in restriction to file name lengths which is enforced on realms server and not on regular servers. I edited all the file names and it worked without problem.