Quicken Classic for Windows - Older Unassigned stock transaction

I have Quicken Classic for Windows R65.29 and I have a question about an Unassigned stock transaction.  I download my Schwab/ThinkorSwim  transactions every week in Quicken.   As I have at least 10 stock transactions I manually assign the SELLs to the appropriate BUYs using the “specify lot” function.   It works fine.   I recently noticed that I had an Unassigned transaction from August 12th (five months ago).  I found it when I ran an Investment report, it shows up as a huge loss, which is incorrect.  I assume that because this transaction is an unassigned SELL the tool does not know the correct gain/loss.

If I go ahead and assign that Four month old SELL transaction to a BUY,  it messes up the SPECIFY LOT totals from August 12th forward to today.   Is there a way to assign that SELL transaction without messing up the other transactions?  

Can I edit that invalid entry in the Investment report? 

FYI I tried running “Rebuild Investment Lots”, that did not fix the problem.