Timestamps vs Frame mismatched

[deeplightanym]

I am using ZED, and I need to use the camera timestamp field in each frame. But the timestamps and frames don't match. I notice the frame loss image 3 & 4, the the timestamp gap is about several frame before the image gap. The timestamps are below:
31741266268420 (Image1)
31741625872831 (Image2)
...(another 2 frames)
31741641732791 (Image3)
31741647174966 (Image4)

We can see that the first 2 timestamps are about 350ms different. But the last 2 images show the frame loss. Can you please explain and confirm how many frames are shifted compared with timestamps?

Image1:

Image2:

Image3:

Image4:

Thank you.