Multigroup drag and drop errors

I have a content type that includes a list of websites in a multigroup widget. The format for this content type is shown below (attachment 1.png).

For each website, there is a category field and a website field. They are displayed on the page as follows (attachment 2.png).

When I drag and drop items to reorder the list, the categories no longer correspond to the correct websites. In the database, the deltas of the matched pair of items are no longer the same.

Here are the category records, including the delta for each record (attachment 3.png):

And here are the website records, including the delta for each record (attachment 4.png):

The records in this multigroup need to always have corresponding deltas so that the correct category matches the correct website.

However, when I drag and drop a group of fields to reorder the list, I am finding that the deltas get changed for either the category records or the website records, but not for both. As a result, my list and my data are a complete mess.

In the example above, the category field is often empty. When this is the case, then only the deltas for the website records are changed after a drag and drop. When there is a one-to-one correspondence between category records and website records, then only the category deltas get changed.

This error does not happen with small lists, say less than 10 records. But for large lists like the example above, which contains 28 records, the error occurs with every drag and drop operation.

Any insight or assistance with this problem would be greatly appreciated!