You should be able to see all of the deal pipelines from the table view for deals. The board view showing all deals is not a feature, as it would require all deal stages to show up in one stream, which would result in a confusing and inaccurate depiction of deals stages.
The option to view ALL deal pipelines is now greyed out across legacy HubSpot Enterprise, HubSpot Enterprise, HubSpot Pro, legacy HubSpot Sales Pro, and HubSpot Sales Hub portals.
Honestly can't remember if/when this change occurred. Hopefully, an easy fix?
You should be able to see all of the deal pipelines from the table view for deals. The board view showing all deals is not a feature, as it would require all deal stages to show up in one stream, which would result in a confusing and inaccurate depiction of deals stages.