Frank Trocchia

The problem isn't with the water blocks being source blocks.  The problem is with how the bubble 'blocks' are generated.  In Java, when you place soulsand/magma block under a column of water source blocks the ENTIRE column IMMEDIATELY changes to the proper bubble block (up or down).

Currently in Bedrock, when you place soulsand/magma block under a column of water source blocks, starting from the BOTTOM a bubble block gets generated, then there is a delay (a few ticks), and then the next one gets generated, until eventually it reaches the top. 

I've diagnosed this with a bubble elevator with a redstone circuit that does the block swapping.   Works fantastic in Java.  Sorta works in bedrock if you WAIT for the entire column to transition ALL of the source blocks to the proper bubble block.

Sorry @Finnegan, but this not really a client side issue.  If that were the case, a server with many people would behave the same a server with just one person on.  

As more people are on a server, chunks fail to load on the client side more heavily.  

Some issues this causes is for flying.  On my server, with three people on, I can fly in the overworld, but do not see any chunks at all.  Nether is much worse.