Scott, I was going to say it might be something in your tap water. I've used both the liquid and the powder developer, and have always had almost identical results with them. Currently I'm using the powder, and my tap water must be of exceptional quality since I have never seen anything like what you show in your print above. That's wild and completely whacky.
What I do with lith printing is that I never use old brown from other developers. Always the same developer, so if I switch from one brand to another I toss all old brown and carefully rinse the bottle it was kept in. I scrub my tray with a well used scotch brite pad every single time before I print. I use a dish brush and scrub my developer tong too (yes, I use tongs unlike everybody else here; they're stainless steel with silicone rubber coated tips and I can easily move 16x20 prints with them). Basically I make sure there is NO chance of contamination. Mixing beakers are cleaned out too, just in case. And in your case it makes sense to use distilled water also.
I'm sorry you're having trouble. Whether you're contact printing or enlarging shouldn't matter. Light is light is light. Shouldn't make a difference, as long as the plates you're contact printing aren't contaminated with something that the Arista Lith developer reacts to.
Good luck, and sorry I didn't respond to your PM sooner. It's been hectic days here.