This bug has been present for many years; see this bug report in the official Adobe feedback forum: Lightroom: Navigator preview pane shows wrong photo | Photoshop Family Customer Community. Please add your vote and details of your issue (especially details) -- the more votes and the more details, the more likely it is Adobe might fix the issue. (Adobe product developers generally don't participate in this forum here.)
See this post for a partial workaround: Lightroom: Navigator preview pane shows wrong photo | Photoshop Family Customer Community
Please continue any discussion in the bug-report topic, so that everyone concerned (including Adobe) benefits.
Changing "Show photos in navigator on mouse-over" (disabling) solves the problem only a little bit.
After doing so, it is not necessary to "zoom-in" to the image to see the right content. It is enought to simply click to the thumbnail.
The primary problem is not a wrong image in navigator pane (I only use this in a few cases). The problem is that I still have wrong previews in library view and in the thumbnails row. This is missleading when I sort or search for pictures.
The wrong preview image is part from a total different file in a total different directory.
Lightroom Catalog Previews.lrdata rebuild without changes
What steps did you take to rebuild the Previews.lrdata? You might try following the steps (perhaps again) for deleting both the Previews.lrdata and the Camera Raw cache: Why And How To Clear Your Lightroom Cache | Lightroom Fanatic
Thanks for the additonal link.
So I can see following after deleting Camera Raw Cache and Previews.lrdata:
I imported 390 new images in LR. At the beginning it seems o.k. But after time it starting to change existing preview pics to some of other pictures. If I click to the image, it takes a little while and the correct preview appears.
But I can see that there is a dependency to Camera Raw Cache because the wrong previes are all from the new uploaded images.
You might try creating a new test catalog and importing several hundred pics into it. Does the problem still occur? If not, that suggests the problem is specific to your catalog, and you could try exporting (as a catalog) all of the pics from your old to your new catalog.
Other than that, I'm out of ideas.
Also I cleand up the cache and rebuild the catalog: After doing so the problem was solved - but only for short time. It starts again... :-(
Adobe says the most recent release, CC 2015.12 / 6.12, fixes this bug: Lightroom: Navigator preview pane shows wrong photo | Photoshop Family Customer Community . Do Help > System Info to verify you actually have that release installed -- LR is notorious for not always updating to "the latest".
Problem still exists:
Version von Lightroom: CC 2015.12 [ 1125239 ]
Lizenz: Creative Cloud
I have 105368 pictures.
Please add details about your symptoms to the official bug report linked above. A screenshot would be very helpful, along with the output from Help > System Info.