diff --git a/cms/djangoapps/contentstore/views/component.py b/cms/djangoapps/contentstore/views/component.py
index 514b89d419..dda94a072e 100644
--- a/cms/djangoapps/contentstore/views/component.py
+++ b/cms/djangoapps/contentstore/views/component.py
@@ -122,10 +122,36 @@ def container_handler(request, usage_key_string):
 
             component_templates = get_component_templates(course)
             ancestor_xblocks = []
+            parent = get_parent_xblock(xblock)
             action = request.GET.get('action', 'view')
 
             is_unit_page = is_unit(xblock)
-            unit = xblock if is_unit_page else get_parent_xblock(xblock)
+            unit = xblock if is_unit_page else None
+
+            is_first = True
+            block = xblock
+
+            # Build the breadcrumbs and find the ``Unit`` ancestor
+            # if it is not the immediate parent.
+            while parent:
+
+                if unit is None and is_unit(block):
+                    unit = block
+
+                # add all to nav except current xblock page
+                if xblock != block:
+                    current_block = {
+                        'title': block.display_name_with_default,
+                        'children': parent.get_children(),
+                        'is_last': is_first
+                    }
+                    is_first = False
+                    ancestor_xblocks.append(current_block)
+
+                block = parent
+                parent = get_parent_xblock(parent)
+
+            ancestor_xblocks.reverse()
 
             assert unit is not None, "Could not determine unit page"
             subsection = get_parent_xblock(unit)
@@ -134,15 +160,6 @@ def container_handler(request, usage_key_string):
             section = get_parent_xblock(subsection)
             assert section is not None, "Could not determine ancestor section from unit " + six.text_type(unit.location)
 
-            # build the breadcrumbs
-            for block in (section, subsection):
-                parent = get_parent_xblock(block)
-                ancestor_xblocks.append({
-                    'title': block.display_name_with_default,
-                    'children': parent.get_children(),
-                    'is_last': block.category == 'sequential'
-                })
-
             # for the sequence navigator
             prev_url, next_url = get_sibling_urls(subsection)
             # these are quoted here because they'll end up in a query string on the page,
diff --git a/cms/templates/container.html b/cms/templates/container.html
index e5e6d84de7..cbe4b1908c 100644
--- a/cms/templates/container.html
+++ b/cms/templates/container.html
@@ -64,7 +64,7 @@ from openedx.core.djangolib.markup import HTML, Text
                 $('.seq_new_button').click(function(evt) {
                     evt.preventDefault();
                     XBlockUtils.addXBlock($(evt.target)).done(function(locator) {
-                        ViewUtils.redirect('/container/' + locator + '?action=new');      
+                        ViewUtils.redirect('/container/' + locator + '?action=new');
                         return false;
                     });
                     return false;
@@ -100,9 +100,17 @@ from openedx.core.djangolib.markup import HTML, Text
                             <div class="nav-sub">
                                 <ul>
                                 % for child in block['children']:
-                                <li class="nav-item">
-                                    <a href="${xblock_studio_url(child)}">${child.display_name_with_default}</a>
-                                </li>
+                                    <%
+                                        # Not all xblock has their own studio page
+                                        # Check if siblings has any url to their own studio
+                                        # page, otherwise avoid including them in dropdown.
+                                        url = xblock_studio_url(child)
+                                    %>
+                                    % if url:
+                                        <li class="nav-item">
+                                            <a href="${url}">${child.display_name_with_default}</a>
+                                        </li>
+                                    % endif
                                 % endfor
                                 </ul>
                             </div>
@@ -123,6 +131,7 @@ from openedx.core.djangolib.markup import HTML, Text
         <nav class="nav-actions" aria-label="${_('Page Actions')}">
             <h3 class="sr">${_("Page Actions")}</h3>
             <ul>
+                ## Hide the sequence navigation when we've browsed into a child of the unit, e.g. showing the child blocks of a problem-builder xblock
                 % if is_unit_page:
                     <li class="action-item action-view nav-item">
                         <a href="${published_preview_link}" class="button button-view action-button is-disabled" aria-disabled="true" rel="external" title="${_('Open the courseware in the LMS')}">
@@ -144,7 +153,9 @@ from openedx.core.djangolib.markup import HTML, Text
                 % endif
             </ul>
         </nav>
+    % if is_unit_page:
     <div id="sequence-nav"></div>
+    % endif
     </header>
 </div>