Different version of Splunk but i had the same issue, there is a KB about it, the thing i found annoying was there is no mentioned of additional permission mention in the docs (i did this in a dev enviroment so i was an full admin). But phantom support was fast to respond
"With versions of Splunk previous to 6.5.3, the Phantom App on Splunk server config or searches hang with the message "updating".
To resolve the issue, add the required Phantom capabilities to the Admin and whichever Role is in use by the Phantom App.
• In the Splunk UI, navigate to Settings > Access Controls > Roles.
• Select the Role name.
• In the Capabilities field, verify "admin_all_objects", "phantom_read", "phantom_write", and "list_storage_passwords" are all applied.
• Save the configuration change.
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