From Jira 9 Atlassian moved all the transition buttons to the dropdown menu. All of the Jira transitions in the dropdown rendering asynchronously on-demand after a user opens the dropdown.
Also Atlassian removed the status field and View workflow link from the issue details section. The View workflow link is shown as an option in the dropdown. The current status is presented in the trigger label.
How to use the classic view on Jira 9
Go to Administration->Manage apps and selectSettings in section Classic Transitions View
You can turn on/off this feature and select projects where you want to use classic view (known from Jira 8)
Add more workflow transition buttons to issue page
When viewing an issue page, most of the workflow transition buttons are contained within the Workflow dropdown menu. Some Jira admins may want to have more of the transition buttons visible on the issue page.
The ops.bar.group.size.opsbar-classic-transitions-view property in the jira-config.properties file is responsible for defining how many workflow transition buttons are shown on the issue page.
Keep in mind that this setting is universal across Jira and will require shutting down the instance. As always, we recommend testing changes in a lower environment before attempting them in production.
Shutdown Jira. Even on Jira Data Center, it is necessary to shutdown all nodes. A rolling restart of the nodes won't suffice.