Lifting and chipping at the free edge generally is a problem either with application or curing. In terms of application, the issue is capping the nails without getting a bulbous edge which will chip later. Fingernail Fixer does a great video on painting short nails that might help. As for curing, I have found that clients often "clench" their hands in the lamp. It's very easy to do with short nails because they don't scrape the bottom like long nails will. Check that the client is keeping their hand flat in the lamp.
Here's the Fingernail Fixer's video:
