AppV_Manage uses the App-V Client PowerShell modules to perform much of its work. This module is signed by Microsoft and untrusted. By default, AppV_Manage overcomes this by adding a "set-executionpolicy -executionpolicy AllSigned" to any script it runs.
This will cause an error if you have a Group Policy object set to require a different execution policy. Even if the GPO sets it to unrestricted, it seems PowerShell won't let you set a temporary more restrictive setting, resulting in errors such as:
Failed to XXX due to the following error: Windows PowerShell updated your execution policy successfully, but the setting is overridden by a policy defined at a more specific scope. Due to the override, your shell will retain its current effective execution policy of 'YYY'.
AppV_Manage has a setting (available on install or on the Tool Configuration tab) to skip attempting to set the execution policy each time.
In addition to fixing this issue, if you set the policy to AllSigned or Unrestricted once either via group policy of just in a PowerShell window (launched as admin) in your image, you can speed up all of the powershell used by AppV_Manage by setting this to skip.