GREP: Zero or more break characters (e.g. ~R*) doesn't work?

Question

I'm trying to make a GREP rule that includes something to pick up any frame break characters at the start, if there are any, and carry on if there aren't.
This should do the job perfectly...
~R*.someGREP
...but it doesn't pick anything up. The .someGREP should happen whether there are break characters or not, but it does nothing. Other things I've tried with the same result:
~R?.someGREP
(~R?).someGREP
(~R)?.someGREP
(~R*).someGREP
(~R)*.someGREP
(~R|.).someGREP
...why are these not working? How can I tell it to pick up any frame breaks, if there are any, and carry on regardless if there aren't?
All of these with a regular character (e.g. 'R') instead of the break character (~R) work as expected.

Answer 1

It's for something using similar logic to the GREP in http://forums.adobe.com/message/5450896#5450896 but for a different purpose.
I'm now doing it a different way, but the original idea was, a paragraph style GREP rule that marks places where frames need to break and styles them accordingly, then a GREP find change on (?<!.)[^~R]+(?!.) and the GREP-added character style, to add breaks to these positions but only if it's not already been done. For this to work, the paragraph style GREP rule needs to apply the character style to any breaks as well as the subsequent text (i.e ~R*.someGREPrule), else the find-change won't be able to see where the breaks have already been added.
I've since found a different approach to the whole problem. But this still seems like a bug.