Issue with Resolution in Fusion when Editing 16:9 Video in portrait for TikTok

I'm trying to create TikTok clips from my stream footage (1920x1080) using Fusion in DaVinci Resolve, but I'm running into a resolution issue.

My workflow:

I change the resolution to portrait in the Cut tab. (Creating a new portrait timeline has the same effect)
I add a Fusion composition inside an adjustment clip and drag it over the section I want to convert to TikTok format.

The problem:

Since the video is smaller than the portrait canvas, when I apply a transformation in Fusion, the MediaIn node doesn't retain the full resolution.
If I set the timeline to "Scale full frame with crop," the video in Fusion is cropped at full resolution, but I can't move the clip to reveal the sides.
Interestingly, if I scale the video in the timeline to fit the Fusion composition size, the resolution remains original. It seems like Fusion doesn’t recognize that the media is larger than what's shown on the screen.

Any tips on how to fix this? I'll add pictures for clarity.