I tried this on the Public Cloud, but I did receive a mail when setting the same options. Could it be that the created mail went to your junk mail folder?
I just created an object with a Contact field and a "Loan Cannot Be Sold To:" field. Next, I created a "Loan Cannot Be Sold Too!!!" e-mail template (with only the contents "Hello") and I created the trigger with the settings shown in your screen shot. When I change the value of the "Loan Cannot Be Sold To:" field in one of the records, I receive the mail.
This is what you also did?
but it did not for me .....
I've tried running the triggers manually and it works... but when I check for the field change to shoot the trigger it doesnt
Please add trigger which creates Audit Trail record, that is much easier to test.