It's been a really hard bug to find! I received this update from our techs:
"Yea we got incoming reports this morning from another partner site. The Dev's are still looking into this issue. Because it's been so difficult to try and track down in order to gather more data it's been difficult to pinpoint. It is at this moment, an ongoing investigation. I'll update you with any findings on their part."
I use Chrome OS and browser and get it all the time. Some days are worse than others. I've learned to ignore it and move on. I just close it out because it did post.