Ok, so not knowing all the inputs, my guess is that you have two lists (paths and profiles) which are not matching. For the sweep node to work you need:
Two corresponding lists: each curve must have its associated profile,
Each profile to be placed perpendicularly to its corresponding (poly)curve.
If you have only one profile, than you have to join all your 1000+ curves into one and then make sure that condition no 2. is true. Where do you take your profile from?
I have regenerated the curves / polycurve and all appears well, however, when l try and draw a profile located a one end of the curve, it still comes up with the same original warning.