Currently we are unable to use Checkbox custom fields as triggers for conditional logic in forms.
It works for Radio Button custom fields, so should be an easy fix - and I think seems to have been forgotten in the release.
I haven't checked all field types, but it would be worth ensuring that all types of fields and custom fields for contacts and opportunities are able to be used as triggers for conditional logic, in case any others slipped through the cracks.
This issue just cost me over an hour's work setting up fields, forms and workflow that will not work because of this limitation.