When I enter the description into a revision table with 'All Uppercase' enabled in the drawing document properties, it appears all caps while typing. When I finish typing and exit the cell, it goes back to lowercase.
Is this a bug?
I am using SolidWorks 2015 SP3.
Yes, that is an confusing behavior. Please report that to your VAR to review and if appropriate, file a bug report. Also, I'm guessing you'd like the All Uppercase available for tables (such as Revision Table), so you may also wish to file/vote-for an Enhancement Request. This will help me work on justification to provide that capability, and it will allow you to get notification of when the Enhancement is implemented.