You may want to try reseting preferences. Wirecast > Help > Send Support Information but instead select the lower left Reset Preferences. Open Wirecast and use a New Blank Document to make sure the problem isn't carried over.
We did environment reset .But We cannnot resolve this issue . And, Uninstall ZIXI Feeder Uninstall Wirecast 9 Even after each installation Zixi did not appear in the selection. Also, I updated the OS to Mojave It was not improved here either.😭