On one workstation I noticed completely by accident that the number of emails is missing and the name of the current folder is not displayed, as in the screenshot, all versions are 10.3.1738, changing skins did not help, additionally some division is the main other. I have many emclinet licenses and only on this one computer do I have it like this.
The Primary and Other tabs are part of the Inbox Categories feature, you can read about how it works, how to change or turn it off on our blog: