I know you were asking about Montana. I have their county ballot returns in a spreadsheet format. The only way to look at this is compare Red County Returns (Yellowstone, Flathead, Lewis&Clark, Cascade, Ravalli) with Blue County Returns (Missoula, Gallatin, Silver Bow, Glacier).
I used 2016 election data to determine red and blue counties.
No deep dive here but at a superficial surface glance it does appear that the “Red” counties are turning in their ballots at a faster pace than the “Blue” counties. Particularly Gallatin, Glacier and to a lesser extent Missoula are underperforming relative to their “red” counterparts in terms of turning in their ballots.
I linked the state website and you can open the spreadsheet and look for yourself (last updated last night 10/29). Click absentee counts by county.
https://sosmt.gov/elections/results/
Thanks. Good work.