Missing categories in myhelp and hr helpdesk page

Hi Experts,
I am facing 3 problems and 2 problems seems to be inter linked and 3rd problem is with category LOV.
1.I was able to create categories and child categories when HZ_ENABLE_MULTIPLE_BU_CRM was "No" and luckily HZ_DEFAULT_BU_CRM profile option value was enabled to "N"
Now, erroneously i made changes to HZ_DEFAULT_BU_CRM profile option value and it is not letting me mark as "No" and forces me to select any business unit.2. But, When i select business unit, and proceed with creating the MyHelp page and Help desk request page, the category field is not showing list of categories i created before.