Embedded form issue: ERROR: undefined method `content_for' for nil:NilClass

[kitebuggy]

Using v4.0.0.beta, standard install.

A standalone, simple form works fine on its own. However, embedding this within an existing page (through clicking on the '+' sign -> Reuse Content -> Choose 'Form' -> Select form and add to page. Error appears in preview: "ERROR: undefined method `content_for' for nil:NilClass"

Stack trace shows:
content_for(html_head, , block) called.
CACHE (0.0ms) SELECT cms_dynamic_views.* FROM cms_dynamic_views WHERE cms_dynamic_views.path = 'cms/forms/render' AND cms_dynamic_views.locale = 'en' AND cms_dynamic_views.format = 'html' AND cms_dynamic_views.handler IN ('erb', 'builder', 'raw', 'ruby', 'jbuilder', 'coffee') AND cms_dynamic_views.partial = 0
Rendered cms/forms/render.html.erb (4.4ms)
Error occurred while rendering Cms::Form#4: undefined method content_for' for nil:NilClass /Users/jason_holloway/.rvm/gems/ruby-2.0.0-p481/gems/browsercms-4.0.0.beta/app/models/cms/view_context.rb:43:incontent_for'
/Users/jason_holloway/Dropbox/Dev/quicktest/beta/app/views/cms/forms/render.html.erb:1:in _app_views_cms_forms_render_html_erb___329539016520353584_70290998819760' /Users/jason_holloway/.rvm/gems/ruby-2.0.0-p481/gems/actionpack-4.0.8/lib/action_view/template.rb:143:inblock in render'
/Users/jason_holloway/.rvm/gems/ruby-2.0.0-p481/gems/activesupport-4.0.8/lib/active_support/notifications.rb:161:in instrument' /Users/jason_holloway/.rvm/gems/ruby-2.0.0-p481/gems/actionpack-4.0.8/lib/action_view/template.rb:141:inrender'
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