[Bug]: MXF file playback is broken

### What happened?

Loaded a Prores/MXF file the Alex reference footage site: https://www.arri.com/en/learn-help/learn-help-camera-system/camera-sample-footage-reference-image -> https://next.frame.io/share/005ff88d-0433-4ce2-bd93-ad94628b1de0/

Plays fine in VLC. In RV it appears to have frozen intermittent frames and then jumps ahead every 7 or 9 frames (eg frame 1,1,1,1,1,1,7,7,7,7,7,7,7,7,7,16....). also the frame numbers seem off and there is a warning in my terminal: `WARNING: Using non-standard frame rate 48000/1`

https://github.com/user-attachments/assets/af2d16ae-8ea3-4a94-9536-90aa23bf5b23

[F003C002_190925_MN99.mxf.json](https://github.com/user-attachments/files/25753780/F003C002_190925_MN99.mxf.json)

### List all the operating systems versions where this is happening

macos 26.3

### On what computer hardware is this happening?

macbook air

### Relevant console log output

```shell
WARNING: Using non-standard frame rate 48000/1
```

### Environment variables

_No response_

### Extra information

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Start by reproducing playback with the referenced ProRes/MXF footage and reviewing the attached F003C002_190925_MN99.mxf.json metadata alongside the terminal warning. Trace how the non-standard 48000/1 frame rate is handled; done means correct frame progression and numbering without the warning.

Written by the indexing model from the issue text.