I detect the same issue. It is not reproduceable for me either. I am working with two SD-cards. I am tagging the images in the camera. Then I ingest on of the cards in PM6 on a windows-notebook and my standard setup in PM6 is to show me tagged images only. This works fine one, two or three times. But after that all images will be displayed. I already did try to reproduce this bug, but I couldn't.
With PM5 this bug never occured.