I had a look over that online help with the snap guides, and still it doesn't show me that little blue circle and the dotted lines that helped me make the walls. Moreover, I have just found that I have another problem. When I try to make a wall, it doesn't create on the line from the plan, and I cannot draw it from the corner to another. ( check the photo below). I really do not know what to do because when I first installed Archicad, that circle, that lines and the walls were working perfectly.
Yes, my snap guides are on, in fact they were enabled since I downloaded Archicad, but I really don't know what is going on with them. I even tried to downloaded it on another PC and I have the same problem, even if I didn't modify something. (photo "snap guides" below).
Anyway, regarding the walls. I am currently drawing on a site plan that was a dwg file and I managed to convert it in Archicad (photo "plan" below). And as you said, if I am modelling very far from my project origin, this what it looks when I am zooming in to draw the walls (photo "zoom walls"). And then when I try to actually draw it, it creates the wall like this, not even parallel to the plan line (photo "walls 2" below).
Moreover, speaking about walls, I also observed that my previous drawn walls are looking like this when I zoomed in more. Is it ok to no intersect at the corners? I don't know how to properly explain this. (photo "walls3" below).
Because of my type of work I have never had a "far from origin" issue, but I believe it results from working with coordinates far from 0,0 which puts pressure on the mathematical computation limits of AC resulting in graphical errors. I'm not sure how you fix it if this is your situation.
Apple iMac macOS Sonoma / AC27UKI (most recent builds)