If I have a variable like "Session" and you want to use it in the immediate window you get this:
"s" -> empty completion window
"S" -> "Session" shows up
In the xml and c# editors it doesn't pay attention to the casing of the variable when filling the autocompletion window.
I can confirm using the latest Visual Studio 2017 for Mac Preview version 7.2 I am able to reproduce this issue. Marking this report as CONFIRMED.