Referenced DWG classes and layers turn off by themselves

[JMR]

Hi,

 

I think I have asked this before but since there has been no answer I'll give it a shot again.

 

For versions 2016-2018 at least, we find that dwg reference viewports on design layers sometimes turn off almost all classes and layers, even though "Use document's class visibilities" is turned off. The viewports diminish into tiny rectangles at the insertion point.

 

I haven't found out the reason for this behaviour so far. It's not any saved view combination, and in any case, these should not have an effect on the dwg viewport if the tickbox is not selected.

 

Please see the attached image.

 

This issue is not version or file-specific, and is not project sharing related, although occurs also on those projects.

 

There is quite a bit confusion sometimes as there might be multiple tiny rectangles at zero representing the dwg viewports with everything turned off.

 

Any ideas?

 

Thanks