Ok, so I've finally recharged and started back with testing. The same problem has presented itself.
When the sight glass was still bubbling, the liquid pressure was climbing above 300PSI, Suction pressure was 90PSI, superheat was high, and subcooling was low. Previous tests started with low liquid pressure and high suction pressure before the original problem when I first charged it up.
Everything pointed to undercharge, except for the high liquid pressure. The low subcooling seems to suggest that it's not a restriction.
I'm confused... I'm kinda thinking TXV or Solenoid Valve... I'm going to experiment later with a few ideas before I jump to conclusions, though.
Any other thoughts?