Google has posted a message at the top of the Google My Business Insights reporting screen that says "data may be delayed." The unusual part is not that the data may be delayed, we see that a lot, the unusual part is that Google posted a notice about it.
Here is the notice:
Google said "Insights data may be missing or delayed due to reporting issues."
Google explained that this has "no impact on the appearance of your business on Google." So rankings and real Google traffic to your Google local business listing is unaffected, this is just a reporting glitch.
Forum discussion at Twitter.
