No, Burns doesn't block many either but it does happen. He averages about 1 every other game (.6). Lampkin is at .1 per game, so he pretty much doesn't block at all. Just for some context, that's about what JJ and Judah were at for the season last year.
I agree that his lack of blocking doesn't necessarily mean there is a problem. There are other ways to disrupt on the defensive end. The big difference that I saw between Burns and Lampkin (when viewing limited highlights, I must admit) is that Burns has more of a burst/quickness where he can get around guys with a very nice move. Lampkin gets more of his buckets from bullying his way to the basket. He doesn't try to juke the defensive guy, he just uses his big body and strength (which is effective).
Where Lampkin appears to be better (versus Burns) is rebounding - which we all know is huge for us. He averaged about 7 last year to Burns' 4. That's pretty big.