The interior of the lube bands aren't touching your bore, its unlikely that's causing the leading issue. At the end of the day, Hi-Tek isn't a cure all, you're still shooting a cast lead bullet. Have you ever slugged your bore to determine your true diameter? Ideally you want want your bullets sized .002 over your bore diameter. I'm sure Brazos will be along shortly to help out.
My first guess would be that it's a sizing issue rather than a coating issue.
However, I did a LOT of experimentation with Hi-Tek a few years ago and it can be very finicky coating to apply. I had batches of bullets that would randomly have coating failures. These were batches made using the same application methods and baking temp/ times that had previously worked for thousands of bullets. I never really figured it out. My biggest gripe with Hi-Tek is that there are no US made competitors to offer a similar product with better technical support. Ultimately, I was never able to come up with reliable answer for the coating failures, my best guess was temperature / humidity variability effected drying and baking times. I kinda gave up on figuring it out and dealt with an occasional bad batch whenever it came up.