10 year old HELOC that Title company didn't pay off when I sold my home.

So about 10 years ago I sold my primary residence that had a First with Wells Fargo and Heloc 2nd..with Washington Mutual Bank.....Chicago Title did the closing of the sale....They accidentally forgot to pay off the Heloc. I have been paying on this loan for all these years....yep..haha So I did a preliminary title search to see what it looked like....
The guy that bought it from me sold. Then the buyer from him went to foreclosure...Now foreclosure buyer owns and rents out the house....Nobody has found this HELOC ..but it seems like it would be like a First Trust deed. I owe $12K
Well now I am trying to buy a house and this loan keeps showing up as a Mortgage...nobody even believes this so It is causing me some grief with the underwriters etc...they even called to verify with the Bank and Now I am afraid it will called due..from the sale...no longer collateral for the HELOC...
Any comments...besides Why the Hell did I pay on it for so long...LOL!! Smooches for the help!!
By the way...Wamu is out of business..now owned by CHASE...they have no loan documents I am sure...haha and chicago title is now like Fidelity Title....they said no luck in getting a title claim now...