This is a screen shot of ~Opera Windows 10: It could easily be a screen shot of Edge Firefox Chrome Vivaldi on either Macos or Windows (or ios/android for that matter). I can’t sort mail except by date (the default), nor does search work properly: except…
…in a fit of frustration I happened to open a portable version of Firefox to find this; working as it should, I presume, searching properly with RB7 (but not RB6). However, for some reason there are two other portable installations, which don’t work. Everything is up to date by the way, and this happens on my work machines and home and so on different routers/ISP
I also noticed this while taking the screen shots, left is Firefox that works, right is everything else that doesn’t (but in this case Opera windows 10, so despite clicking synchronise index it clearly isn’t doing that, because I’ve never seen a stop index synchronization message; and yes when I first go into RB7 it says something like wait while we synchronise your browser.
Other than telling the portable app where to install I have done nothing special in installation, and I’ve tried a portable installation on my home machine. I’ve also switched of all extensions and done clean reinstalls.