did you ever resolve this? I'm now seeing the same thing, though with HTTP!
At first I thought it was my aging WinNT4.0 CA that was the issue, but now it's started happening to my Win2003R2 CA as well.
OK, we've managed to sort it in our environment.
The main issue turned out to be that we had spaces in the name (CN) of the CA, which in turn put spaces in the path/URL for the CRL.
It looks like the CRL validation in LiveCyle doesn't properly escape the spaces (as %20) and so it is unable to download the CRL.
Depending on your environment, you may also need to check that the LiveCycle server can connect to the location of the CRL via HTTP.
We've got a firewall in the way which caused a secondary problem for us.
Hope that helps.
BTW Big ups to Uday at Adobe Support for getting me to the point where I was able to resolve this.