Yes it does.

But you have already troubleshooted the problem by running the Cat6 across the ground. The next question is 'how did 2 Cat6 runs go bad in conduit, that were burial rated'?

1) Did you supply the Cat6? What is the brand & part#? How long has the cable been in the ground? If someone else supplied it, anyway to find out where they got it from?
It has been noted many times in the past, how cheap cable can cause problems and even have lies attached to the listings. One reason I always argue for the use of quality cables that are properly listed, for uses that are going to be more or less permanent.

2) Did you install the cables in the conduit? Or did someone else do it? Wondering how much pull was done to the cables installing. Usually direct burial cable has stiffer more robust jackets and can take more than the regular 25-30 ft lbs of pull. But if it was pulled more than 50-60 ft lbs, I would suspect the cables might have been damaged. Not uncommon for damaged cables to start giving trouble years later, after having marginally worked before.