Randomly strewn throughout my minecraft map environment seems to be blocks or blockspaces where I can't place a block.  Water does not flow through the block.  I can't place a another block on this "invisible block".  Mining does not remove or interact with it.  However, my character can pass through these blocks as if nothing is there. These random blocks seem to be "remembered" despite restarts of the OS and Java Launcher. 

I was using this launcher and realms world prior to 1.16.1 in the prior latest release 1.15.2 and there were no similar issues.  I have attempted to roll back to prior releases, but only get the error message that the Realms world is incompatible with these other Launcher releases.

I detected this issue when I had water runs that were unbroken through the upgrade from 1.15.2 to 1.16.1, but when I made a change after the upgrade suddenly the water paths were blocked by these invisible blocks.  I had run into other issues similar to this when mining or building, but thought they were transient and temporary glitches.  However, since I've noticed it when building these water structures, I've realized they are persistent and interrupt my game play.

Thanks for looking into this!