Hi David,
It looks like the data is being truncated so it is missing a closing tag and possibly other tags in the xml.
Can you verify that the field SerializedItem is of type nvarchar(max)?
This data type should hold up to 2 GB of text so it should not be truncating.
For now I would delete the remaining rows in mp_IndexingQueue and see if the problem comes back again later.
How many rows are there in the mp_IndexingQueue table?
Best,
Joe