I have a field type of checkbox, which is set to be ticked by default. It is set
as an "optional" field for all groups in the FEU module.

I have included the checkbox in the self registration form. The values which are
stored when a new user registers are:

- 1 for checked 
- "false" for unchecked

Once I log in after registration, the correct information is shown in the "edit
details" section i.e. the checkbox is checked or unchecked depending on what was
chosen during the registration process.

If the checkbox is checked on registration, I can uncheck it in the "edit
details" section and the correct value is saved.

The problem occurs when the checkbox is already checked. If I try to uncheck it
and then save the details, it says that the data was saved but it isn't; the
checkbox remains checked when you view the "edit details" page again. It also
reports that the value is still set to 1 if I debug the variable in the foreach
loop in the template.

I am using the default template.

CMSMS version 1.11.10
FEU version 1.23.4
Self registration module version 1.8.2
CGExtensions version 1.38.11
CGSimpleSmarty version 1.7.3