We have been having a problem with Sitecore in Azure PAAS – it appears that when auto-scaling scales out, App Services are being put into rotation before they have started up. This is causing all sorts of weirdness.
Sitecore support recommended making sure that we had Application Initialization configured. That seems a good idea. I’m not sure why the guys who set up this instance didn’t; perhaps they were unaware of it (and to be fair, it’s something I’ve not looked at before).