Endermite portal particles are emitted about 1 block below where they actually are, causing them to not even be visible most of the time.
Step to Reproduce:
1. Spawn an Endermite on top of a glass block
2. Look at where the particles are appearing, it they should be inside of the glass block instead of where the Endermite is
Expected Result:
The particles appear where the Endermite is
Observed Result:
The particles appear 1 block below where the Endermite is