even if the eggs looked good when they were first laid they might not have been fertile. it takes about 2 weeks before you can candle leo eggs and see veining. at this point, if they look yellowish instead of pinkish when you candle them and you don't see veins you know they are infertile.

i have never used vermiculite to incubate leo eggs so i'm not quite sure about the moisture levels with that. i use perlite and mix a ratio of 1 parts perlite to just more than 1 part water by weight--probably close to your 60% to 40% ratio. it does not seem that wet though--you want it to be just barely moist (again, this is perlite that i'm referring to). you might consider trying a 50:50 vermiculite/perlite mix.

if your eggs are molding they are either too wet, infertile or have gone bad. in my experience, once they start to mold they don't stop and go completely bad. this is regardless of what steps taken to try to save them. i have only succeeding in saving eggs that were too dry, but never ones that were too wet. don't toss them until you are absolutely sure though--once they stink and turn cheesy you'll know it's time.

i've never heard anything about using antibacterials or any other substance on eggs and wouldn't recommend it. i don't know what affect that might have on a developing baby inside and wouldn't want to risk any ill effects. some people will only mark their eggs with a pencil as opposed to a sharpie or other marker to avoid any negative effects of from the ink soaking into the shell.

i'd recommend that you just start over. remix your medium and put some perlite in with the vermiculite. perhaps the vermiculite alone is too wet.

what are you incubating in and at what temperature? you should be getting some condensation on the inside of the container and should wipe this out every few days. there shouldn't be so much that it is pooling up, dripping from the top onto the eggs or requires wiping every day. if this is the case your mix is too wet and should be remixed with less water.