If you have blocks in an orphaned block region then drag and drop ordering can produce inconsistent results after a page refresh.

The easiest way to see this in core is in the Boost theme on a default installation.

As a user with the default Dashboard:

1. Go to your Dashboard page
2. Add three HTML blocks at the Top of the Right column in the following order:
   • HTML block title and content: Block 1
   • HTML block title and content: Block 2
   • HTML block title and content: Block 3
3. Click on the drag icon for Block 2
4. Click on To item "Block 1" in the drop menu
5. *Verify *that the order of the blocks is now:
   • Block 2
   • Block 1
   • Block 3
6. Click on the drag icon for Block 1
7. Click on To item "Block 3" in the drop menu
8. Verify that the order of the blocks is now:
   • Block 2
   • Block 3
   • Block 1
9. Refresh the page

Expected outcome: the blocks are in the same order

Actual outcome: Some of the default blocks are now above the html blocks

This happens because the default blocks they are set to be in the side-post region (which is the right side in Classic) rather than the Right region. After following the original steps that did not delete the default blocks many of the blocks changed to have a region of Right.

Both the Boost and Classic themes have a side-pre region, in classic it is on the left, however in Boost it is on the right side. So it looks as the the problem is that it breaks strangely when blocks with a region that is not part of the current theme are present.