IMS Navigation broken

[gjb2048]

Ref: https://moodle.org/mod/forum/discuss.php?d=332513

EssentialTest.zip

[gjb2048]

Notes:

I've recently installed the Essential theme 3.0.1.2 (Build: 2016010206 2016010207) on Moodle 3.0.3+ (Build: 20160331). Unfortunately, it appears to break IMS Content Package navigation for all lessons that we have on our site.
I've tested with More, Clean, Bootstrap (and our old Standard) themes - IMSCP navigation works fine.

With Essential, the forward button is the only nav button clickable but only changes bold emphasis on the navigation menu. Clicking on links in the nav menu takes me to the correct page of the IMSCP but in a new page and not within the existing IMS display window.

1. Add an activity or resource - IMS content package
2. Click add and then fill in course name and upload (drag and drop) the EssentialTest.zip package file that I've attached.

3.After saving, click on the Essential IMS Content Package and you will see something like the following (we have customised some Essential colours):

I've shown you a little of the Moodle page context as well as the IMS display.

1. It should be possible to click on the navigation buttons on the left to work through the pages of content. However, only the forward button is clickable (different colour) but it does not change the content in the window.
2. It should be possible to click on the structured menu on the left and view the content in the IMS content window. However, clicking on these menu items takes you to the correct content but on a new page with no Moodle formatting.
3. The functionality is correct when using any of the themes mentioned in my original post.

[gjb2048]

Update to replicate:

OK - here's what I've done.

1. Fresh install of Moodle 3.0.3+ (Build: 20160331)
2. Added a new course and inserted an IMSCP activity using EssentialTest.zip which I supplied previously.
3. Tested - all functionality correct
4. Installed Essential theme via Plugin Installer and 'Install plugins from Moodle plugins directory' - theme not selected at this point
5. Tested - all functionality correct
6. Selected Theme (Essential 3.0.1.2 [Build: 2016010206] 2016010207) - all default values
7. Tested - navigation problem as before - TOC links take user to a new page and buttons remain dimmed - fwd button moves highlighting on TOC links but no content changes

Other server info:

PHP Version 7.0.5.2.1

MySQL Version 5.6.28.1

[gjb2048]

Happens in FF and not Chrome. Other themes not affected bar Shoehorn. Common element is fitVids, but could be others. AntiGravity not as ok in Shoelace.

[gjb2048]

FitVids is the problem.

[gjb2048]

No idea how to fix this.