Egg binding can happen with fertile or infertile eggs, even in the best of conditions and animal health. I had to have a female spayed last year due to egg binding. She is and was in the high 700 g's and has always lived full time with her mate. It would have been her 2nd clutch last year. She laid 2 eggs normally and then could not lay anymore.
I have never had a problem with females laying infertiles. Most likely my dragon had one egg that was too large for her to pass causing the egg binding condition. Infertile eggs cannot have this problem.
The biggest cause of egg binding is husbandry. Things like dehydration, temperature and improper nest area are the most common causes.