Hi GeoStudy,
Do you have the same problem mentioned in this thread? That is, when you digitize new points, are they not created at the mouse cursor position?
Also, which GPlates version are you using? And are you using Windows?
If it’s the issue with wrong Qt5 DLLs getting loaded into memory, then GPlates 2.5 has a potential fix for that. Note that the previous solution I mentioned here doesn’t fix it (ie, simply copying “gplate.exe.local” after GPlates has installed won’t work - it has to be part of the GPlates installation - which is the case with GPlates 2.5).