Improper cost tracking (BeMob and PropellerAds)

[AffiliateNate]

In BeMob, the revenue and conversions for my PropellerAds campaigns are being tracked perfectly. However, the cost values are being improperly tracked in BeMob, as are the visits on BeMob (which I imagine is inevitable).

1. Is the improper tracking of the cost a consequence of the fact that some of the impressions from PropellerAds don’t get tracked as visits in BeMob (and so the reported costs are less)? If yes, how do you deal with this in general?
2. Is there any value in trying to reduce the discrepancy in the number of impressions reported on PropellerAds which are not tracked as visits on BeMob? (To be clear, it’s not clickloss I’m talking about here - I don’t think - but “visitloss”... let’s call it.) If yes, how do you deal with this in general?