When you pick up lava at the same time that you die the lava will become invisible... also, it doesn’t apply liquid physics to the player, only burns them...

To reproduce:
Turn on keep inventory
Set spawn point very close to lava
Go into survival mode
Jump into the lava and try to pick it up at the last possible moment with a bucket.
If it succeeds then you will have an empty bucket and there will be no lava.
Here is a video that shows this bug and how to reproduce it: [video| https://drive.google.com/file/d/1eMhCUSI_A0c85fUN76bVQo3h0yd0wbTG/view?usp=drivesdk

Notes:
if it is updated it will reappear
I believe this might be related to MCPE-65291