Premiere Pro: "Scale down when playing unsupported frame sizes" setting is not working.

I'm on an iMac Pro with Ventura 13.5 using Premiere 23.6.0 (Build 65)

In the past with OS Catalina, I was able to select the playback setting *Scale down when playing unsupported frame sizes *and larger than HD clips (for example UHD clips 3840 x 2160) on the Source side would play through as HD clips in my HP Monitor connected with a Blackmagic UltraStudio SDI interface. That was good and it worked well.

Now with a Blackmagic UltraStudio 3G interface with Ventura 13.5 using Premiere 23.6.0 (Build 65), it does not work. If I try to play a UHD clip from the source side with an HD sequence (1920 x 1080 at 25 fps) loaded, the audio gets muted for both windows (source and program) but the video plays, which makes it
totally useless.

So, in order for it to "work" I have to keep the setting to *No output*,
which is not ideal. With this setting, I see/hear the UHD clip on the Source side only, not in
the HP monitor. The HD sequence plays normal and fine.

It seems as if the option *Scale down* is not working.
Is this a bug or is there a solution?

I consulted with BlackMagic support and they said the problem is on Premiere's end.

Thanks.

Rubén Abruña