Bio Distiller number readings are 0 all the time

it is probably waiting for enough slime to start the job. works in batches of 30kg afaik

Since they changed everything to all-or-nothing those stats aren't updated 10 times a second like before.
You'll see it briefly when it completes a cycle then right back to 0.
 

Look at it for longer time. Dupes will come to collect algae. Like Risu said - It will only show produced number for a second. Notice the animation as well - the drawer from smaller part of it will open for the time they collect it.