A plausible scenario for this: you intalled the main part without installing the subparts (or placed them in a wrong folder). When you look at the part with LDCad, it misses all those subparts as shown in your screen capture. If then you look at your file with LDView (or try to make BIs with LPub3D that uses LDView), LDView automatically fetches the missing subparts from LDraw server. Its display is correct, and the missing subparts are now correctly placed in the right folder, thus "repairing" LDCad display.
Maybe future versions of LDCad could also try to fetch missing files from LDraw server?
Maybe future versions of LDCad could also try to fetch missing files from LDraw server?