Missing units in FBA shipment

Good morning everyone, i’ve recently sent a parcel to the amazon logistical centre, and it seems like they are missing one of the units i’ve sent them.

I am sure i’ve sent the right product with the right labels (i even have a pic of it for some reason!) and i am sure they did receive the parcel because the tracking says so.

I went to the shipping page and selected the option “research missing units” and even sent a message to the support to solve the problem asap.

In the meantime, i have 2 doubts:
firstly is there anything i could do? Should i provide Amazon with more info regarding my shipment?
Secondly, how often does amazon take the blame for similar events and reimburses its users?

Thanks to everyone reading this