This is weird since last night it did work here, after months of 100% fails. Edit: I had GIT pulled so maybe the latest code for whatever reason didn't make it into the nightlies? Are you running 18.04 or 16.04? I saw the 16.04 AMD64 version failed to build.
If you have the logs with GUIDE enabled, then it might shed some idea. What's the build date for your KStars? You can find this in the Help --> About KStars window.
There's a known issue reported in the forum that relates to odd coordinates passed for subframing by PHD2 to V4L2 CCDs, if that could ever be the case for some of you.