Descript version: 139.0.19

OS: Windows

Project type: Video, Portrait 9:16 (1080×1920)

Bug description:

All portrait compositions export as 1280×720 landscape regardless of composition orientation settings. The canvas preview correctly shows portrait layout, and layer/composition properties confirm 1080×1920, but the exported MP4 is always 1280×720.

Steps to reproduce:

Create a new composition, set orientation to Portrait (1080×1920)

Import any portrait video file (tested with 1080×1920 native .mp4 and .mov files)

Add video to script track

Export as MP4

Output file is 1280×720 landscape

Expected result: 1080×1920 portrait MP4

Actual result: 1280×720 landscape MP4

What was ruled out:

Not source file metadata — reproduced with multiple portrait sources including a native 1080×1920 .mov with no rotation flags (verified via ffprobe)

Not VFR/variable frame rate — reproduced with CFR-encoded sources and non-slo-mo footage

Not a single file issue — reproduced across 10+ compositions with different source files

Composition orientation is correctly set in UI; canvas preview looks correct

Impact: Unable to export any portrait video from Descript on Windows. Affects an entire project (10 compositions).

Workaround: None found on Windows. Awaiting test on Mac/web app.