Hi Everyone!
Lily here from the HubSpot product team 
This week we released the functionality of “View all” in the sidebar for custom objects. Now, when you are on a custom object record, or viewing custom objects on other records, you have the ability to click “View all” and be taken to the index pages.
Thank you to all for the feedback around custom objects. We recognize there are a number of areas of improvement listed here, but do hope you will benefit from this update in the sidebar.
Cheers!
Lily