After receiving the LC1800, I read the Owner's Manual. Noted on p. 2 is the following Line Conditioner Connection Warning: "If you are connecting your Line Conditioner to a motor-powered AC generator, the generator must provide clean, filtered computer-grade output."
Tripp-lite LC series (600,1200,1800,2400 etc) power conditioners have been used endlessly with basic ac generators with great results,i was never aware of that warning, but i did just check the site and i see exactly what you mentioned, i only know they work well from many others who have recommended them to me.
the idea does not even make sense, if my generator ( or any other power source have "filtered computer-grade output" why would i need a line conditioner with filtering at all, when an AC voltage regulator for ~$25 would work just fine.
Not sure if they are just saying that for longevity or something, but i know these boxes being used for camping , with 300-400 hrs or maybe more and no failures.
did you try it yet, or are you returning it?