Optimized Media and Fusion messing with my image size

Hi, I'm running the Free 16.2.0.54 build [EDIT: I have upgraded to v16.2.2012 and the problem persists], and I'm having this issue where my clips get scaled down for no apparent reason. I'm overlaying a mobile screen recording to a 16:9 FullHD (but the same happens in 4K) background/timeline.

If I use the mobile clips as imported everything works as expected, and the clips touche the top and bottom edge of the frame when scaling is set to 1.

If I generate Optimized Media (set to auto) the clips get scaled down, so they're not filling the frame in height anymore even though their scale is set to 1. However, when rendered, they get scaled back up (I imagine it's because DVR uses the original files for rendering).

The same scaling happens if I use the original clips (the ones working fine), but edit them in the Fusion tab (placing the playhead on them and heading to the Fusion tab, adding a Paint node to clone some icons away, and going back to the Edit page). These clips, when rendered, do not go back to their original size, and remain scaled down.

I'm attaching a screenshot taken from an output file that further illustrates the issue.

Thanks in advance for your help!

What are the dimensions of the mobile clips? What are your settings under Project Settings>Image Scaling?

The mobile files are 1080x2220px, while you can find the scaling settings attached (they're set at the default).

I have looked further into this, and found out something that could be relevant: if I play the original mobile clips in an external player (VLC), the clips fills the frame top to bottom as expected (and as it happens in DVR). If I open a clip in the Fusion page, though, it becomes surrounded by a transparent border all around, that seems to match the "crop factor" I'm getting in the reported issue (see attachment).

Thanks for helping!

For posterity: I had a similar issue and fixed it by setting the Input Scaling to "Project"