We recently released a managed package, and came across a strange issue. We have overridden a custom object Tab with a Visualforce page. When I click on the Tab, the page shows up as normal, but the Home tab is "selected" and not the Tab I just clicked on. This is the only tab this is happening with, none of the others are affected.
As you might imagine, this leads to a very confusing user experience. I checked that the tab has "Default On", and the object has CRUD permissions, but this is happening to both Administrator and Standard Users. Has anyone experienced this before?
The Home tab is selected because it is the default when no other tabStyle is explicitly specified on the page tag.
Your VisualForce page needs to have the tabStyle attribute set to the name of your VisualForce tab in order for the page to highlight this tab.
Per the Salesforce docs on the apex:page tag: