ISSUE: Profile Manager does not show a code signing certificate when asked to sign configuration profiles. 

Please try to import the intermediate certificate files manually on the IOS device through the following URLs:

1.      Intermediate 1:https://support.comodo.com/index.php?/Default/Knowledgebase/Article/View/966/108/intermediate-1-sha-2-comodo-rsa-certification-authority  
2.      Intermediate 2: https://support.comodo.com/index.php?/Default/Knowledgebase/Article/View/984/108/intermediate-ca-2-comodo-rsa-code-signing--ca-sha-2

You can also refer to these URL for more information:

• https://discussions.apple.com/thread/4079265?tstart=0
• https://discussions.apple.com/thread/5661074
• https://discussions.apple.com/message/27510469#27510469