Bugs on Apply Copied Filters

[Microwave-WYB]

OS: Arch Linux
ShotCut Version: 24.06.26

To reproduce the problems:

• Import some clips
• Set multiple filters on the first clip, for example, "Fade In Video" and "Fade Out Video"
• Click the "Copy checked filters"
• Select all remaining clips, right click, select "Apply Copied Filters"

After these steps, we can see the problem:

1. The timeline is not updated with fade-in/out filters. Only the first clip is displayed correctly (with fade-in/out indication)
   
2. starting from the third clip, the fade-out filters are ineffective. Although it's displayed on the filter list, there's no fade-out effect (as you can see in the screenshot, the preview at the last frame of the third clip should be black if the fade-out filter is correctly applied)
   
3. After manually updating the filter parameters, the timeline is finally synced with the filters. This is a screenshot after manually updating the fade-in duration (the fade-in is displayed on the timeline but the fade-out is not)
   
4. However the workaround does not fix the problem that the fade-out filter is ineffective. As you can see, the timeline is displaying the fade-out filter, but the last frame of the clip is not black.
   
5. Another problem: if I undo applying the filters, the filter list is correctly reset. However, the timeline is not updated. The fade-in/out effect is still in the timeline. (maybe the timeline update can be tracked in a different issue?)