Microsoft have updated the Unified Interface’s UI with big improvements to the Sitemap and Command bar.
I have been facing this issue in unified interface, I did a lot of research on this and followed the below steps to resolve
We first need to get the organization id, this can be found in Settings > Customization's -> Developer Resources
or type the below command in Console
//Xrm.Utility.getGlobalContext().organizationSettings;
Xrm.Utility.getGlobalContext().organizationSettings.organizationId;
Open CRM Instance -- > Press F12 --> Console (execute the below scripts)
Xrm.WebApi.online.updateRecord("organization","{ORGANIZATIONID}", {"clientfeatureset":'<clientfeatures><clientfeature xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-Instance\"><name>FCB.ShellRefresh</name><value>true</value><location>Organization</location></clientfeature></clientfeatures>'})
Xrm.WebApi.online.updateRecord("organization", "{ORGANIZATIONID}",
{'clientfeatureset':'<clientfeatures><clientfeature xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-Instance\"><name>FCB.DashboardCustomizableRibbon</name><value>true</value></clientfeature></clientfeatures>'})
Before executing Script
After executing the above script in Console window, we can see the button
E = "FCB.Client.Chart.DrillDown"
W = "FCB.DashboardCustomizableRibbon"
P = "FCB.DisableEditableGridControlOnPhone"
T = "FCB.LookupService"
N = "FCB.LookupQuickFind"
That’s it , your custom buttons will be available now in UCI.
