This looks like it's related to a known issue <https://code.google.com/p/googleappengine/issues/detail?id=13041>, as instance IDs for Flexible instances are not being logged.
On Saturday, July 23, 2016 at 4:13:22 AM UTC-4, Ben Rometsch wrote: > > I have 2 flexible VM instances running. In the console, the graph (that > used to work back when they were "Managed VMs") shows zero instances? > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/google-appengine. To view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/9f40d789-34d1-4c43-b825-a911c5e9f88e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
