Cause

The below record (with Assembly name) is missing for "RemoveSSLBinding" custom action in ISClWrap table. All other custom actions have this record.

The record mentioned above for that particular custom action was deleted accidentally by editing the table or by performing some other action in the UI.

Solution

Change 'Run 64-bit PowerShell script' value to No and again back to Yes to get the missing record back. This will fix the warning during the build.

The logic behind embedding required resources\assemblies for managed custom actions is based on Assembly attribute. In order to optimize the space, InstallShield collects and groups the required assemblies for all custom actions and embeds the required assembly only once.

In this case, Assembly attribute is missing for this particular custom action, hence the empty value was assumed and the warning was shown.