Visual Studio Editor - Block Unindent

In Visual Studio 2013 (Version 12.0.40629.00 Update 5) editor, with [Micro Focus COBOL] Tabs set to 4 & 4 and Insert spaces on ....

... you can highlight a block of code (that let's say starts in column 12) and hit the tab key to indent it, and it will move it to column 16 ... which is the expected / desired result.

However, if you hold down on shift and hit the tab key to Unindent it, it moves it back to position 13, not back to the expected / desired position 12.

It appears that this only happens if the "block" consists of more than one line.  If it is just one line, it handles it correctly.

Thanks.