I have had reports over the last few months that OTP for access to services behind ZeroTrust often does not go through. I have seen this myself where I tried multiple times over the course of several hours and had exactly one email get received and one that was received well over 15 minutes after the attempt (which makes it expired, of course). The latest ephemeral issue that was resolved is unlikely to be the cause unless this thing happens very regularly (multiple times a month). I know there are quite a few issues similar to this one out there without resolution.
（I’m also having the same issue of not receiving emails）