More often than not, when I start mining, 1 or 2 or 3 miners won't find shares, or they find 1 or 2 shares then stop.
I've heard a few similar reports but only have 2 devices currently for reproducing issues. I do have some remote access to machines with more for doing more investigating.
That said the build of BFGMiner out there is just past the "It Works" stage and there's been a lot of changes since then. Once 4.0 is closer (probably today / tomorrow) I'll release another build. If the issue still exists then I will start working with individuals to address it.