Copy /Paste or Select All/Move Has Incorrect Sizing in Photoshop 22.5

[Linns2]

I am trying to copy and paste a photo  (4"x6") from one document to another (8.5" x 11") both at 300dpi and the size is greatly reduced in the new document. It's the same for Select All using the Move Tool. The new image appears as a thumbnail and I have to use Transform to resize it correctly. This shouldn't be. I have tried 

making sure the documents are both zoomed at the same ratio before transferring, but the problem is the same. Any suggestions? Thank you.

MacBook Pro/ Big Sur 11.5.2

[Linns2 · Accepted solution]

Looks like an error of mine. It was set to 300 pixels/centimeters, not pixels/inch.