How to remove/disable auto-value-set on a custom field (user picker - single user)?

Jimmy Li_0lfoyu

I have a custom field (user picker - single user) named PM that gets auto set to the currentUser after create. I am trying to remove the auto-set but not able to find how the value is auto set. Places I've checked

1. The custom field's default value is empty (and there doesn't seem to be any support for setting "currentUser" as default value)
2. There's no automation rule (project and global level) that sets value on that field
3. Checks installed-apps and don't see any that would set value on that field

Other things I've tried

1. Created another custom field (user picker - single user) named Dev. This field didn't get auto set when creating issue.
2. Created another JIRA project of same type (Classic software project). The PM field didn't get auto set when creating issue.

What else can set value of a custom field when creating issue?

Thanks

Jack Brickey

Can you check the workflow post function on the create transition?