Object display in larger assemblies

Hello,

Some of the parts in my assembly appear differently than they should:

The bolts somehow received a conic head instead of the regular hex head

And this is how I want to view them:

We use screenshots to show progress and thus I'd like the bolts to be represented as they should. I've tried changing how to load the large assembly, setting things to lightweight, but the problem persists.

Oh and on the drawing itself the bolts also appear with a conic head instead of the regular hex head.

What gives?

thank you.