Autocorrect is producing errors

I am wrestling with auto corrections on my Win8.1 installation of Scrivener. When I type the word hadnt it autocorrects to handt and then it autocorrects that to Handy.The words handt and Handy are not in any word list that I know of here.

I tried to fix it via Options > Corrections > Edit Substitutions, by entering hadnt to be replaced with hadn’t but that resulted in Scrivener autocorrecting to hadn’tt. Then I removed that. Later I added it in again and now it autocorrects to Haydnt.

The tt at the end of apostrophe words happens with other words too.

I added hadn’t to my Personal Word List but that made no difference.

Ideas?

I’m using the American English dictionary but I see no easy way to access that to see if it’s corrupted or to correct it.

A new online friend who is somewhat of an expert with Scrivener feels there’s a bug in my system. Fwiw, I have Malwarebytes and it’s up to date. Ditto Microsoft Security Essentials. Both scan frequently.

UPDATE:
I deselected Enable additional substitutions and that has taken away the hadnt error but it still turns bodnt (a nonword for testing) into Bondy.

Thanks.