Applying the effect to Vert. video crops final image

New to Fusion here. I've got a timeline 1080 x1350 (4:5 vertical video for Instagram) and turned video on 90 degrees there, after aplying any effect in Fusion using a Rays node (for example). The image's aspect ratio is changing to 16:9, while my timeline is 4:5 (my intended render aspect ratio).

When I to Edit, the image is cropped on the sides (black bars). Meanwhile the fusion frame format 4:5 as well (please take a look attached pictures). I don't see any settings in Fusion's "transform" panel to ignore the original aspect ratio... and really I'm surprised it doesn't do this by default.

I must be missing something obvious.

step 1 - video on time line before fusion

step 1.jpg (176.2 KiB) Viewed 271 times

Step 2 - Applying effect

Step 2.jpg (245.92 KiB) Viewed 271 times

cropped video in Edit timeline

cropped video in Edit timeline.jpg (167.97 KiB) Viewed 271 times

Can you put your MediaIn1 into the first viewer and zoom out a little so we can see the resolution in the upper right corner of the viewer like your Viewer2 in the 2nd picture? The resolution of your MediaOut1 is 3840x2160. In my example below, I added a 1080x1920 vertical video to my timeline that I set up for 1080x1920 when I add a LightRays node to it the resolution stays the same.

My source footage is 4K, which i turn on 90 degrees left and scale to my timeline 1080x1350 resolution.

Screen Shot 2019-12-26 at 5.22.39 PM.jpg (354.98 KiB) Viewed 234 times

First thing, before adding anything to the Media Pool or anything to the Timeline, go to the Project Setting and set the Timeline resolution to Custom - 1080x1350.
Then add your footage to the Media Pool and add it to your Timeline, no need to rotate it 90 degrees in the Clip Attributes. Right-click on the clip and click "New Fusion Clip". Then switch to the Fusion tab and you should be able to work on your footage in 1080x1350.