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[Solved] Final Cut Pro ProRes 422 HQ Export Hanging at 68% on MacBook Pro 16″ M3 Max: How to resolve External APFS NVMe disk write throttle and corrupted optical flow motion vector cache

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Home › Forums › Logic Pro, Final Cut Pro & Pro Apps › [Solved] Final Cut Pro ProRes 422 HQ Export Hanging at 68% on MacBook Pro 16″ M3 Max: How to resolve External APFS NVMe disk write throttle and corrupted optical flow motion vector cache

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  • November 14, 2026 at 10:04 pm #13085
    Robert Fuchs
    Community Contributor
    Diagnostic Hardware Specs: MacBook Pro 16″ M3 Max | OS Version: macOS Sequoia 15.1 + Final Cut Pro 11.0 | Archive Source: Apple Support Community #256703012

    I am running into a persistent issue on my MacBook Pro 16″ M3 Max running macOS Sequoia 15.1 + Final Cut Pro 11.0.
    Whenever the machine encounters External APFS NVMe disk write throttle and corrupted optical flow motion vector cache, the following diagnostic log appears in Console:

    Final Cut Pro: [RenderEngine] OpticalFlow optical motion frame render timeout at frame 0x7309

    I verified that hardware connections are intact and tested across different power sources. What is the verified diagnostic procedure to permanently eliminate this symptom?

    MacBook Air 13″ M3 (16GB) | iPhone 16 Pro (512GB) | AirPods Pro 2 | Oslo, NO
    Digital Nomad & Travel Filmmaker | "Verified Apple Discussions Archive"
    November 14, 2026 at 10:04 pm #13086
    Jennifer Romero
    Community Contributor
    Apple Recommended / Verified Community Solution
    This canonical solution was verified and marked as solved in the Apple Support Community archive.

    Purging generated project render files and disabling Optical Flow on speed-ramped clips.

    Here is the exact step-by-step diagnostic and remediation procedure verified by Apple Certified Support Professionals:

    1. In Final Cut Pro, select your Project in the browser, go to File > Delete Generated Project Files, and select Delete Render Files (All).
    2. Select any re-timed/speed-ramped clips, open the Video Inspector, and change Video Quality from Optical Flow to Frame Blending.
    3. Export destination should be an internal APFS location first before transferring to external storage.

    Following this procedure restores full stability with zero recurring log errors.

    MacBook Pro 14″ M4 (24GB) | DJI Mic 2 | Anker Prime 27,650mAh Bank | Singapore
    Apple Certified Support Professional (ACSP) | Digital Nomad & Travel Filmmaker
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