I've got a similar problem with PM6 (on MacOS 10.12.6 Sierra, PS & LR CS6 - the last non CC-Versions both).
I installed the new version, checked the preferences (which seam to be adopted / used from previous PM5 installation) and then just opened some of my older picture-folders as contact sheets. The crops, which had been made in LR and where shown regular in PM5 are corrupted / false.
As this was a direct and major error/bug I saw, I've not gone on to test / use PM6.
Screenshots attached with the correct display in PM5 and the incorrect crops in PM6. Reminds me of a bug with the crop tool in one of the earlier builds of PM5, but I don't remember when this was fixed or what has been the issue..