Trapped Chest contents shift in converted worlds

My world used to be in version 1.12. 

When I loaded the world into 1.13, the top three rows and bottom three rows of almost all my double chests switched positions.

For example, in my afk fishing farm from before, I put all the stackable junk items at the top of the chest, and now the order is reversed. 

In chests with all the items are the same (for example a chest filled with dirt), this doesn't make a difference, but its annoying that I have to reorganize a lot of my items.

There appear to be some chests that are not affected at all, but I haven't been able to find a clear pattern. If it is any help, I heavily used the fact that in previous versions, you could place trapped and normal double chests right next to each other.