Gmail lossy email system

For months I’ve been noting that email to my 2 different GMail accounts (one for work on the business side using the Google Apps for business, and yes, paid for … and one for personal) are not getting all the emails sent to it.
I’ve had customers reach out to me here at this site, as well as calling me up to ask me if I’ve been getting their email. Seems I’m not the only one, though the complaint here appears to be a bad filter and characterizing system. My complaint is emails that do not make it through.
Back in the day, when I used to run my own email servers for the office, I didn’t normally have a problem with mail. We had a deeply pipelined spam/virus filter that could handle pretty much anything we or others threw at it. Even this site has that same tech, and we’ve used it for years. Handled attacks just fine. We wouldn’t lose mail. That is something that is simply not acceptable.
You can mischaracterize it. False negative/positive on spam. But losing it? Never. Unacceptable.
So why is GMail losing so much of my mail? I don’t have a transmission or loss probability right now, but I am thinking, seriously, of automating a set of tests to see what fraction get through.
No, the emails don’t wind up in SPAM. They don’t wind up anywhere.
Very frustrating. And I don’t like black boxes I can’t look into.