Hmm, I tested the simple case in both LR 5.7 and LR 6, and the virtual copy shows up in the smart collection.
Make sure you don't have any filters set in the Library Filter bar.
And can you post a screenshot of the smart-collection criteria?
The screenshot was very helpful. The problem is with the Custom 05 custom metadata field. Which plugin defined that?
It appears that smart collections don't properly search the custom metadata fields of virtual copies. I filed a bug report in the official Adobe feedback forum: Lightroom: Smart collections don't correctly search custom metadata fields.
You could work around this by using a filter preset in the Library Filter bar. Perhaps not as convenient, but it would get the job done.
Hi John ! Thanks for your help ! It is the plugin Search Replace Transfer of John Beardsworth. It is in many way's a very helpful plugin in my workflow.
For your bug report; i'am using LR5 latest version (although i have a cloud subscription, but no time to check all my presets etc. while upgrading)
I will try your trick with the filter bar ! Thanks a lot ! Hope Abobe will come up with a solution in short time ! All the best ! Bart