This occurred with Beta 4 although I suspect it applies generally. I was surprised last night when I restarted a paused sequence on a Flat event and SGP complained that the guider (PHD2) was not connected. My expectation is that SGP should only check for guiding when starting a Light event and not Flat, Bias, or Dark events.
SGPro does not check the type of frame it starts with, but rather checks to see if any light frames are in the sequence. It is designed to run unattended. SGPro knows it will need to guider at some point regardless of the first frame type so it complains about it while you are still in front of the computer.
However, in this case it was only a Flat event. There where Light events in the sequence but they where all disabled (e.g. not checked). So it appears the test should ignore Light events and targets that are not enabled.
I won’t be of much help to you without the logfile and sgf file you were using.
Might be related to the new PHD2 checking that was just inserted this last release. I’ll check it out.