I use a QHY5 on PHD using the ASCOM V5 to connect. I have no problems with the graph and last night polar aligned using a piece of software called
PHDLab.
It uses the log that is created (it needs to be turned on) by PHD and can also graph in real time. When you turn off the guiding in PHD and let PHDLab know that you are drift aligning it will give you a measure of how far off alignment you are. You can then adjust your RA & Dec on the mount and get instant feedback as to how you're progressing. I managed to get my alignment error down to ~5 arcmins last night which I was happy with.
I hope this helps....
Cheers,
Mario