Problems with lines and commands in perspective view (SOLVED!)


So I try to draw a line from the bottom corner of the box to the upper corner, but I can’t it stays flat… I could do it a few days ago on the perspective view but now I can’t and I have no clue why…

I try to make the ‘lid’/ of the box a little less high but that doesn’t work either but I could do it before now I can’t… Can someone help me with that please

Like when have a simple box, I can’t draw a plane surface on top of the box it stays flat and I can’t move it either

CUBUS_EbruKoyuncu.3dm (107.2 KB)