Multiple Guest Orders assigned to Single Customer - Customers unable to process returns

We are on the released version of v4.2.

Several guest customers are checking out fine however there orders are assigned to a single "guest" customer.
This, in turn - prevents the customer from later opening an account with the original email address and being able to check order status or process a return as the orders do not carry over.

We attempted to utilize the FoxNetSoft AutoRegisterGuest plugin as a stop-gap for the bug in nopCommerce, however there are still some customers receiving Guest accounts despite setting this popular plugin to auto-register on order completion.

Utilizing the below query I am able to identify the customer IDs in question with a large volume of orders.

SELECT TOP 100 c.Id, COUNT(o.Id) CustomerOrderCount, CONCAT('/admin/customer/edit/', c.Id) CustomerUrl
FROM [Order] o
INNER JOIN Customer c
  ON o.CustomerId = c.Id
GROUP BY c.Id
HAVING COUNT(*) > 1
ORDER BY CustomerOrderCount DESC

This is causing some difficulties as we are in the interim manually assigning orders to the new Customer ID via SQL (locked field in Admin GUI).