Corrupted images in AdvaPIX TPX

A customer in Japan is testing our AdvaPIX TPX and they have encountered a technical issue with the measured frame data:

They took 10000 frames and some of the frames seems to be masked, as you see in the graph.

Where could the a problem?

Checking directly the data: here are the min/max and average signals:

The corrupted frames are with ID 15 and 16. The frame 15 is:

frame_15

and frame 16 is:

frame_16

An example of OK frame is:

frame_17