I'm attempting to troubleshoot a weird issue. We are running SharePoint 2013 Enterprise on a farm of three WFEs and two App boxes. The three WFE boxes are in a load-balancing pool so that one server doesn't get all the traffic. When users connect to one of the WFE servers (let's call it Box 3), they are unable to drag and drop documents into a new library. The error they get is:
The documents cannot be uploaded because different permissions are needed. Request the necessary permissions.
If they connect to either of the other two WFE servers (Box 1 or 2), everything works normally. The issue can be duplicated, and I've tested with multiple users. The common denominator is definitely which WFE they're getting site content from at the time of the error.
The site is using a custom master page but there aren't any custom ASPX pages or scripts copied into the hive folders on each server. All three servers are running the same build number and services. All three servers should be configured exactly the same as well, but obviously something is missing or incorrect on this one server. The correlation IDs & event logs haven't yielded anything helpful as far as I know.
What configuration setting or file could be causing this issue?