I have both measures too. Both drop drop ZIP, Bullseye and 2400 with dead solid accuracy for me. When I start loading, I weigh every charge, then every 10th, then the 25th and then every so often if I don't see any changes.
The variable charges occur at the beginning of the process for me. Once everything settles down I don't see any variations in load.
Have you thoroughly cleaned the LnL before setting it up? It comes with a rust preventing coating that has to be removed with a solvent. Hornady recommends One Shot cleaner w/Lube. Others have recommended brake cleaner to remove the coating. Also wash the powder tube with dish detergent and dry it. Then rub it inside and out with a dryer sheet to kill static buildup.
If the coating isn't removed, the powder measure is known to throw erratically.