Good question T28B, I see what you are getting at. Other pilots on this forum have indicated that the area has marginal VHF voice coverage.
If the ACARS data is transmitted VHF-only, and all of the ground stations sites are just on the edge of the VHF ACARS range, one could assume the possibility of ACARS data drop-outs.
The decoded reports such as what we have seen so far would normally only show the error-free messages. I presume there are recordings of the raw data that can be further dissected.