Connectors not showing in Revit

[Tadasana]

I have inherited a duct Revit model from a former employee and I am noticing that certain connectors do not show up in the Revit model.
In our Fabrication database (which is linked to the Revit model) there are many sizes of flange out connectors but the only one that shows in the Revit model is 1 Flg Out.  These all show correctly when working in Fabrication (2020) but when applied to duct in Revit, the connectors look like they are RAW.
I have exhausted everything I can think of that might be causing this - does anyone have any ideas?  The general has us coordinating down to the 1/8 of an inch, so accurately modelling the connectors is kind of important.
Thanks all.

[edsharp]

i know it sounds weird but with our revit if these 2 line colors dont match it will not show in revit... not sure if this applies in your case if it works on one machine and not another

[Tadasana]

That seems to have solved the problem - not something I ever would have thought of.  Thanks a million!

[craigjonnson]

Bizarrely, this happened to me yesterday. Colour 2 changed to 1. No-one has messed with this.