You mention several things in the message. PHD2 is probably more accurate than PHD - the interface is more advanced and it works more intelligently with other applications. You probably are experiencing poorer seeing conditions.
Plate solving sometimes needs a helping hand. It can work without a clue but it is quicker if you can tell it roughly where you are pointing and what your image scale is. Image scale is the angular resolution of the sensor. To know the image scale, you need the focal length and the pixel size of the sensor. Have you typed those into the equipment profile?
There is another current thread on centering errors - there is quite a bit of discussion - for some, there is no issue at all and others have issues. There are a lot of mounts out there and a few settings that may trip things up. In your mount (ASCOM?) settings, can you set J2000 or JNow? That might be worth a try. I need to read up on the thread again and see if there is a general conclusion and some things to try.
One thing with SGP (and PHD2) - these programs create log files. It is diagnostic information that can help others work out if you have a problem or not. These are text files and the developers pretty much insist you share those before they try and root cause analyse. It might be a good idea to set up a dropbox or cloud based drive to share these. There is a drop down menu in SGP that displays the log file folder. I don't want to overload you right now -