NVEnc crashes after conversion from MP4 source to MKV AV1 NVenC

**FastFlix Version:**
5.12.2
**Operating System:**

**Describe the bug**
A clear and concise description of what the bug is.
When coding an MP4 video file from h264 to AV1 using NVEncC AV1 profile, NVEnc crashes after coding is complete. It probably does not matter the source codec, just that the resulting file is AV1 NVencC and that it crashes at completion.
Let it be noted that I have an RTX5090, the log states 4090. Doubt that has anything to do with it as MKV to AV1 does not crash.

**To Reproduce**
Steps to reproduce the behavior
Open an mp4 video file.
Ensure setting is set to AV1 NvencC.
Convert Away!

**Screenshots**
If applicable, add screenshots to help explain your problem.


**Logs** (If applicable) In FastFlix you can go to Help > Open Log Directory and sort by latest to find the newest log file to add here.

[flix_gui_2025-07-08T11.06.07.log](https://github.com/user-attachments/files/21125163/flix_gui_2025-07-08T11.06.07.log)

[flix_conversion_Video1_2025-07-08T11.35.28.log](https://github.com/user-attachments/files/21125238/flix_conversion_Video1_2025-07-08T11.35.28.log)

Please make sure to remove any personal information or video names in the screenshots and logs!