Tabs disappear when moving horizontal tab items or vertical tab items to a new group

I'm not sure whether this is related or not - the features module is not enabled on my site, I am however using RC2 of Field Group and I haven't used or upgraded from any other versions. I have two content types set up which both contain a horizontal tab group and horizontal tab items. The first content type which I haven't touched recently is working as normal. Whereas the second is behaving oddly since upgrading to the latest dev of Ctools.

First of all, only one out of the three tabs were displaying on the node edit form. I decided to test by changing them to vertical tabs in a vertical tab group and still the same, only one tab is displayed. I then tried moving the three tab items out of the group. They are then displayed on the node edit form at the bottom in the vertical tab group that contains the menu settings etc, which I believe is the correct behaviour. Also tested that if they are set as horizontal items without a group, they are displayed as collapsible fieldsets on the node edit form.

I was starting to think it was a setting I had wrong somewhere but the items and groups are configured exactly the same in the first content type which is working correctly (still haven't touched it). I then decided to create a new vertical tab group, deleted the old vertical tab group and moved the 3 items into the new group and now all three tab items have disappeared on the node edit form!

I have now just tested by creating a new content type and if I again create the horizontal group followed by three horizontal items - it all works fine. If I then create a new horizontal group and move the items from one group to the other, the items disappear again from the node edit form. There is actually only one tab displaying but it contains none of the fields. I just edited the first content type (which was fine) and it does the same, that too is now not displaying any tabs.

I cant be sure if the upgrade to Ctools did this (or if it was there previously), but I upgraded that module last night and this existing issue made me think the two could be linked?