Holy cow, Tom... I think you just inadvertently provided me with an answer to a question that's been plaguing me for some time. I didn't put it together. Whenever I disconnect from Windchill, Unite works (at least enough to open a SolidWorks 2016 file). Whenever I'm running a linked session, I get the ATB error. We actually own ATB and have it enabled, too... but we don't have the collaboration extension yet. I should've caught this but having you point it out no makes it seem obvious. Of course that's the problem!
Hey PTC... one license man... just take a bucket of money and give me everything. I am sick of playing with your weird licensing schemes. Geez, man... for the love of all that's holy please simplify this mess.