I'm using a Mechanical Press to create clay blocks in my machine. Whenever it fills up its amount of output that it can have, it will halt its process until the basin has room, except that it doesn't continue. It will fill with clay and clay blocks, get emptied of clay blocks, and not create any more. I'm feeding clay in through a mechanical belt and feeding it out through a funnel.
Edit:
create-mc1.16.5_v0.3.1.jar
forge-36.1.2
1.16.5

Addressed in 0.3.1c, thank you for reporting!