I'm not sure if anyone else picked this up or not but the issue with the Union Query is not a glitch.  What it's doing is switching you to an SQL view because the query designer does not support doing a union query.  

If you look at Microsoft's support page regarding creating a union query in access it reads:

"Unlike normal select and action queries, tables are not related in a union query, which means the Access graphic query designer can't be used to build or edit union queries. Youll experience this if you open a union query from the Navigation Pane; Access opens it and display the results in datasheet view. Under the Views command on the Home tab, you'll notice that Design View is not available when you work with union queries. You can only switch between Datasheet View and SQL View when working with union queries."

So, when it's "blanking" the screen it's changing to SQL view and since there's not design view available for union queries it's not pulling any information over automatically that you may have put in there before hitting the button.  It's simply starting from a clean SQL page with nothing in it because you have to build them from scratch using SQL.

If you notice, when Richard clicks on the button or you do it yourself, down in the lower right corner of the designer you will only have an icon for datasheet view and SQL view.  There won't be the third icon for the query design view you would normally see for other query types as it's not supported for union queries.  

Hopefully this isn't a repost as I didn't read all of the comments but it may help someone to know it's not a glitch.