Nether Roofs for biomes this hasn't been fixed as of August 2020.

Here 

MCPE-91101

 

I been told that this was going to be fixed 3 weeks ago,

As of August 12, 2020, it hasn't been fixed with the release of 1.16.2. I have report this bug it was a serious bug that destroy the basalt deltas and soul sand  valley reputation.  Meaning less interesting like in Java.

 

Thank you.