A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
This is a user-to-user forum, so none of us can speak for Microsoft about when a fix will come along.
That said, the reports all seemed to involve Excel update 15.3.1 and that was a release from long ago. No one has said they have updated to the current version, which is 15.19.1.
So that we're all on the same page here, the first thing to do is install the recent updates. Make sure your Mac has a working internet connection, then:
Update Mac OS X. Open the App store and click on the Updates button. Install the updates.
After, in any Office application go to the Help menu and choose Check for Updates to launch the AutoUpdate app. Let AutoUpdate install updates.
Go to the Excel menu and choose About Excel and verify that you have version 15.19.1. After updating, please reply as to whether or not the problem continues to exist.