Linked models vanished

I am working on a project in Sketchup/Enscape with quite a few linked models. They have somehow disappeared from the Enscape viewport, but are still positioned in Sketchup and are linked to the correct files. I don’t know what caused them to disappear as I was working in just SU for while without Enscape open. I hven’t relocated the files on my HD, so how do I get these files to be visible again?

Nothing on this page is helping:

https://learn.enscape3d.com/blog/knowledgebase/linked-models-win-sketchup/

I’m on a deadline, so need to know how to restore these files asap!

Further to this, when I try to copy and paste one of the original models back into the sketchup file so I can re-make it as a linked file it only shows an empty box, and still doesn’t show up in Enscape. This is an awful bug!!!