lower coverage observed than actual 
I was trying to run mosdepth on few large *bam* files (40 GB) generated from human data. I ran mosdepth without `-n` option and calculated the *average autosomal coverage*, it was way lower than what it was previously calculated by some other tool.  To confirm, I loaded the bed file in IGV and found that mosdepth actually reports *2* less coverage at some spots than its actually observed. I am wondering what is setting this *coverage calculation* off