Output Scaling Problems on Ultrastudio Monitor 3G

Hey there, everyone. First time user on this forum, I've been reading up on a lot of similar topics but can't seem to find the solution for my particular situation. Context: 1.5x Anamorphic 4K footage from Sony FX3.

So I have a project timeline set to UHD 4K outputting 1080p HD to a BenQ PD2700U Monitor via the Ultrastudio Monitor 3G from my Macbook Pro 2017. For some reason, the scale of the output image on the monitor is zoomed/cropped in by a lot. I tried messing with the basic Resolve preferences and also the project settings but nothing seems to work. NOTE: It only happens with this particular project!

Solutions I've tried:
1. At first, I thought it was due to my anamorphic footage (I adjusted the pixel aspect ratio to 1.5 on 'clip attributes'). So, i reverted it back to square that left me with a desqueezed but normal 4K footage. The zoom just became more evidently clear.
2. Due to this being a scaling issue, I messed with the 'image scaling' controls on the project settings. It is already set to monitor in 1080p HD and 'scale entire image to fit', but for some reason it's not scaling the image to fit at all.
3. The only temporary fix I've found to display the image correctly on my output monitor is to scale back the image to 0.5 on the Edit page. Thus, the output image on my monitor is correct. But, this results in the viewer on my laptop becomes very small because the image is downscaled 0.5 on the timeline.

Anybody ever experienced this issue? I personally have been using this I/O Box for more than a month, and I've only come across this issue now. Other projects (I've only tested on one other project) in 4K output normally so I really don't know where I've gone wrong.

I've had this issue before. The issue at least for me was a mismatch of the Timeline Video Monitoring resolution and the Deck Playback resolution which is found in Project Settings > Capture and Playback

First, in case you have project settings being overridden by the timeline lets turn that off for now while we troubleshoot. If you are using Timeline Setting to override the project setting, you can copy the working settings back to this after we solved the issue with just using Project Settings to keep troubleshooting simple.

1. Right click the timeline in your bin and select Timelines > Timeline Settings...
2. In the bottom left corner, make sure Use Project Settings is enabled. Everything should be greyed out now.
3. Click OK.

Next we will adjust the monitor and deck playback resolution settings.

1. Open Project Settings by clicking on the Gear Icon next to the House icon on the bottom left of your window or Shift + 9
2. Regardless of what your timeline resolution is set to(leave it at whatever is correct for your anamorphic footage), in the Video Monitoring section make sure the Video Format matches the maximum resolution of your Blackmagic Decklink/UltraStudio device.
3. Next go to the Project Settings > Capture and Playback. I think this is where your issue is.
4. In the Deck Settings section, make sure Video Capture and Playback is set to the same value you chose in Master Setting's Video Monitoring Format.

Basically, we want to make sure the timeline is sending out an HD sized image for monitoring purposes so that the image "fits" 1:1 into the maximum resolution supported by your UltraStudio 3G > Then we want to make sure the UltraStudo 3G is not trying to additionally scale the image by making sure it is set to the maximum resolution it or the monitor can support, whichever is lower. > The HD signal is then sent to your BenQ which will then handle the up-scaling to 4K so it fills its own display.

At this point your image on your monitor should be showing up not zoomed in to the center HD portion. (Don't forget to get rid of your .5 scaling!)