Appending ribbondebug=true to the record’s URL adds the new Command checker button in the command bar, which could help us in troubleshooting any unexpected behavior with ribbon.
More on this – https://powerapps.microsoft.com/en-us/blog/introducing-command-checker-for-model-app-ribbons/
Recently we added one enable rule to an existing button (Go Live) in the Customer Journey table. The rule was calling a JavaScript web resource based on the security role assigned to the user hiding or showing the button on the form.
Click on the Command checker to open the window on the side pane, where we can then select our button.
In the command properties tab, we can see our custom enable rule showing an error.
Also here clicking in View rule definition solution layers provides us the detail that this rule has been added as part of an unmanaged layer.
Clicking on the Unmanaged layer further provides us with the definition of the enable rule.
Going back to the error, we figured out that the function was missing from the web resource, and adding the function fixed the issue for us.
Back in the Command checker, we can see the custom Enable Rule getting evaluated correctly.
Check the Troubleshooting Guide
Hope it helps..
Nishant Rana's Weblog 