Two other things I've thought of.
Would touching the emulsion cause the second problem? I'm using a guillotine paper cutter to dice up 8X10 sheets and so I handle the paper.
Also, I was mixing the A and B concentrates in the tray not separate and adding. I'd put 2L of water in the tray, add the A, stir, add B, stir, add old brown and stir. Is it possible the concentrates being added like that don't play nice?
This is the powder version of the Arista which I found out is not the same as the liquid arista...