Happens Constantly with our server- But specifically when loading ocean chunks. I had my server crash, 5 times within an hour :/
Still confirm that it's still around in 1.14 pre-release 1. And I'll be honest- I haven't hated something in an update more, makes building in creative and with command blocks super frustrating.
I also have this bug on our test server- We don't change render distance but it will take up to 20 minutes to get a chunk to load when joining or teleporting to it.
So I've done a proper mob count. With only 1 Person on. There are 1950 hostile entities. I did this by adding a tag to each hostile mob and then killing them using ./kill @e[tag=hostile].