Table drag layout is broken when multi value field is placed in a vertical tab

Also my multi value image field doesn't display the field label when in a vertical tab.

This does however work fine when you click "Show row weights". I haven't gone in to the code thoroughly but I'm guessing the non JS version is loaded first, then field group does its thing, then tabledrag tries to convert it to the js version, and then it screws up after that.

Further debugging:

misc/tabledrag.js (Around line 121)

Drupal.tableDrag.prototype.initColumns = function () {
// ... 
      var headerIndex = $('> td:not(:hidden)', cell.parent()).index(cell.get(0)) + 1;
// ... 
};

This only finds headers that are not hidden. Placing these fields in vertical tabs obviously hides the headers. Perhaps this is a core bug, or perhaps this could be resolved by calling something like Drupal.tableDrag.prototype.initColumns() on the table when the vertical tab is activated, which I guess would be another core issue.

Wow I wish I found this earlier. #303189: Tabledrag doesn't hide columns when the whole table is initially hidden

Commited to 8.x and 7.x.