LrC Workaround for International VA - Smart Previews Cannot be Viewed

Been scratching my head on this one...

I have been employing a VA for some months to train and assist in editing of my preschool photos.  Currently, we are on v13.5.1 (Win10) and will remain here for some time until later this year.

Here is the issue...

I send my VA the catalog along with the Smart Previews, Preview, and .lrcat-data db's.  This information is exported from a known catalog that is not corrupt and is kept fairly clean (frequent catalog optimization).  When the VA opens the .lrcat file, he gets an unknown error and cannot open it any further.  We have tried to open Lr and then the catalog and also open the catalog directly.

A workaround was found rather by accident by the VA and that has worked more or less until now.  He found that if he renamed the catalog that I sent him to example.lrcat.lrcat and the Smart Previews db to example.lrcat Smart Previews.lrcat (adding the .lrcat where shown), then for some reason, he could see the smart previews.  We have way to many raw images for him to download and work with directly (we are in the US and he is in the Philippines), so this is not a solution.

So, why does the workaround work most times?  Is the issue related to location?  Are catalog exports bound by region?  Why can't he view Smart Previews out of the box?

[Moved from ‘Bugs’ to ‘Discussions’ by moderator, according to forum rules.]