Failed to schedule... cb, [EROR] messages in our logs

So we are seeing an abundance of “Failed to schedule get commands”, “Failed to schedule remove commands”, “Failed to schedule upsert commands” in our Couchbase 4.5 logs. I’m not a developer, just the system admin, but would like to try to bring this to the attention of our developers, if I only knew where they are coming from and why they might be happening?

Can someone explain to me why these types of errors might be getting logged with our Couchbase Servers (On Windows 2012)? We are using PHP7 and PHP SDK 2.6 with IIS on Windows.
Where should I start to look for what might cause these particular errors, or are they even really errors? Is it a sign of another issue we should look at or can they just be ignored?