Investors & landlords

Thx.  I simply followed steps in TurboTax (used it for 20+ years) and ended with what I got.  The only thing I did differently this year was checking "Yes" when asked if I sold the property in 2017. I noticed a large negative value showed up on Line 22 of Schedule E  (it was always 0 in previous years) that came from Form 8582.  I don't know why Form 8582 got activated this year.  Any suggestions?