Which ad providers are you using? Mine are set to: "Commonly used set of ad technology providers". Maybe I should hand pick the 12 under "Select ad technology providers". However, all my other apps are close to 100%, but are only affected if they are pulling in interstitials.
I can't advise you , but I have picked the 12, and on average always get over 90 % match rate.
Maybe It's worth a try, I won't give my preferences here , but you can always email me, at
sizzgamesrwz@gmail.com
By my calculations if you say you have 746,00 network requests and you were getting 90 % match, that would equate to 671,000 requests, if you got a 1/4 of those requests as impressions, that's 168,000 impressions, on an average of £2.00 rpm(revenue per thousand impressions), you should get £336.
So, you should sort it out sooner than later.
cheers