Categories missing after Exchange online migration

If the colour categories are missing on a shared mailbox after a user has been moved to exchange online, this can be resolved by doing the following.

1: Right click on the category bar at the top of the inbox (where the columns are listed – From, Subject etc) and you should see the following menu :

2: From the menu click on View Settings which will show the view settings menu :

3: Click on columns, and it will open the show columns menu. On the left hand side click on Categories and then click add. You can then click on OK and it should add the categories column back in: