Is there a weld bead in the part itself, as it looks like it is picking this up in the drawing?
If possible, could you please upload the part file to take a look at?
since you are uploading the drawing you will need to do the part as well or do a pack N go to zip ( my fav). Other wise we have nothing but an empty drawing.
Can you grab an end point on the caterpillar and drag it? I haven't used these for a long time so i don't remember.