Photoshop to Light Room Issues

One of the threads you quoted says "Save back into LR"

You do not save back into LR, you have to re import.

Otherwise the previews will not be updated.

If you use LR then choose "Edit in" (from LR) then hit Save (not save as) then the preview in LR will automatically be updated. No matter if it is a PSD file or otherwise.

Like others have said, please provide more detail of the problem.