I am using LL12 with Delphi 2007 for a report that was based off the code used in the invoice demo app.
The designer and printing work without problems but when I try to preview the report nothing displays. Everything appears to be working, no error messages - the preview window just never opens.
The only difference that I can see is that my app is using dBase data instead of MS Access so I had to customize my DefineVars() and DefineFields() procedures.