this is a bit of a first for me. I have an electrical panel assembly full of components and when I move that in to a drawing most (but not all) of the components disappear! You can still wander around the drawing and pickup on their edges but they are not visibly there. Perhaps even more interesting is I may see parts of an assembly (eg a DB connector) but then not the assembly it is a part of!
I did manage to find this thread https://forum.solidworks.com/message/514813?q=parts%20disappearing and tried the CTRL-Q but it did not work. I've also tried creating a new drawing, copy/pasting sheets, rebuilding, rebooting, etc. I am really at a loss for this one. Interestingly enough there are no other drawings in this project I am having issues with - I have used many of these same parts in drawings previously and not had issues.
here is a link to the pack-and-go (44mb) https://files.viengineering.com/url/3mdythcy269vnktk
here are screen shots of the assembly and drawing: