Solution
The TestStand 2019 installer does not include IVI Step Types. You can install them with a separate installer. The IVI Step Types installer is included in the USB stick that ships with TestStand and in the ISO available in the Individual Offline Installers link in the bottom right of the
TestStand download page, as seen in the image below:

Once you have downloaded the .iso installer:
1. Mount it by using one of the methods listed
here.
2. Open the AdditionalInstallers folder.

3. In the AdditionalInstallers folder open IVIStepTypes folder.

4. Run the autorun executable or the Install executable.
5. When asked to select the bitness, select 32-bit.