Photoshop Bug: Mockup won't show (some of) the Smart Object content

[MikaFromDenmark]

Can anybody explain to me what is happening here or how I can fix the problem?

I often work with mockups, but this problem have never happened to me before.

I tried inserting a thumbnail into the Smart Object, but somehow doesn't appear when I save the Smart Object.

I've tried restarting Photoshop several times and even tried opening the workfile in the 2024 Beta version of Photoshop too, but with the same problem happening.

Any fixes?

[MikaFromDenmark]

Okay, so for some reason my video didn't attach, so now I've uploaded it here:

https://www.youtube.com/watch?v=YXGNR73tOn4

[Michael Bullo]

Can you elaborate on what you mean by "I tried inserting a thumbnail into the Smart Object"?

Are you opening up the Smart Object and placing content on the top layer?

[MikaFromDenmark]

At 0:11, I go into the mockup Smart Object, then at 0:19 I go into my linked PSD (actually not a Smart Object, like I described it in the post). I place a new piece of content in the PSD at 0:34, hits save and closes that PSD. Here, the mockup Smart Object should have updated with the new image, because of the linked PSD, but of some point does not?