There is no items in dropdown menu of Packer Installation

I installed packer-plugin on plugin management page.
I added packer to publisher step but I can do nothing anymore.
No item is not shown in dropdown menu of Packer Installation.

What should I check to run?

Reproduce the issue from the plugin management page, then follow the Packer publisher step where the dropdown is empty. Check the plugin installation and publisher-step behavior first; done means the expected selectable item appears and the configuration can proceed.

Written by the indexing model from the issue text.