Setup:
Processing Array with IV power input
EV Tier Pulverizer in the Interface

Behaviour:
Tricalcium Phosphate Ore stays in input bus. Doesn't get processed.
Every other ore tested works

If I downgrade the Pulverizer to HV Tier Tricalcium Phosphate Ore gets processed.

Do you have enough space in your output bus? With the vague description provided, I have not been able to reproduce this issue.

Yes the output bus is empty. The problem is that with EV Tier Pulverizers in the Machine Access interface, Tricalcium Phosphate Ore doesn't get processed. Every other ore does. As soon as I downgrade the Pulverizers in the Machine Access interface by one tier the Tricalcium Phosphate Ore also gets processed.

Found the source of the problem. Ive had 4 energy input hatches but only 2 were connected to power. But it was no problem with not enough power. Just the fact that not all were connected.