Hyphened arguments are not passing to views

What I have?
- ctools 7.x-1.0-rc1, using Page manager, Views content pane.
- views 7.x-3.1.
- Panels 7.x-3.0

I got already created a view which is called from a panel, the panel has a string as context which is fetched form url. that is: http://webpage.com/home/!isodateformat

this string context has an ISO date format YYYY-MM-DD, however the view seems do not apply that filter, so I tested this:

Send argument using pane's contextual option. using html-safe or raw-string
-Don't Work

Send argument directly in argument pane.
-Don't Work

Stablish argument in view configuration, in "Preview with contextual filters:"
- Work

So, when I test the string YYYY-MM-DD (with hyphens) directly over the view, it works perfectly however when I call it in Panel's pane it doesn't work as It should do it.

If this issue is duplicated or has been wrongly assigned as ctools issue. plz take the proper actions.