When I try to place a manual support (which is all I use) the support will appear at the head when I try to attach to the feet, or not appear AT ALL.  This is after I downloaded Chitubox onto my new laptop...I even tried v1.8.0 beta and am having the same issue.  Not sure if its on your side or mine but I read a few threads from a while ago (V1.4 or 1.5) that had a similar issue which was a bug.