I am also having this problem. Several months ago I upgraded from 4.13.7
-> 4.17.10, and about two thirds of data dropped off and hasn't
recovered since. . We've cross referenced our data with google play
console, and we see no drop off. Edit: The drop off is drastic on
Samsung, google, Motorolla, and LG manufacturers (the most popular).
There didn't seem to be a drop off in Sprint or US Cellular, although it
we might not have enough data confirm that these manufacturers aren't
affect.