When a .tss file contains certain grammars, Titanium Studio cannot parse for display in the Outline View, and the entire Outline View goes blank. Examples:
The colors line contains an array of objects. This is a legitimate style in a tss file, but its presence causes the whole outline view to go blank.
The top:10, has an extra comma in it. This isn't necessarily a correct grammar, but a .tss will compile with it in place. However, it breaks the Outline View for the entire page.
I use the Outline View quite heavily when working with tss files, it's hard to go without a working tss. Example 2 has an acceptable workaround, but Example 1 does not.