Nintex Forms Administration is missing in Central Administration even after re-deploying the .wsp solutions. When navigating to: Central Administration > System Settings > Manage Farm Solutions the NintexFormsXXX.wsp and NintexFormsXXXXcore.wsp solutions are both deployed to the Central Administration web app without error.

Run the following PowerShell command from a SharePoint Management console:
Enable-SPFeature -Identity "NintexFormsAdminWeb" -url http://ca:8888 -Force

Note: Replace the "http://ca:8888" with the web app. url and port number for the Central Administration site.