On my 1040 Schedule E form for my 2018 taxes, my two investment properties both had a loss and the loss is displayed on line 21 however line 22 is 0. Why?

It looks likeyour investment properties are listed as "passive" properties.   Losses on a rental that are passive are not deductible.   If you materially participate in the activities of these investment properties then you can change the category from passive to non-passive.   By changing it you'll see the losses on line 22.  Renta losses are deductible up to $25,000.

Here is some information on this:

Rental activities are considered "passive" activities, and a loss on a passive activity is not deductible against non-passive income, such as wages. A special rule lets you deduct up to $25,000 of losses from rental real estate in which you actively participate. The $25,000 deduction is phased out when your modified adjusted gross income is from $100,000 to $150,000, resulting in no deduction above $150,000 (for a married filing joint return). See IRS Publication 925 for additional information.