If the error "Proposal is not associated with a legacy survey" shows when trying to view a deal, the V2 deal has been disconnected from the V1 lead. This happens when a lead or deal is deleted from the leads or deals table because the deal does not delete or archive in V2.
If clicking the lead name on the deal shows the error, "we can't find what you are looking for, Customer not found" this verifies that the lead has been deleted. In this case, the lead and deal will need to be recreated.
If clicking the customer name takes you to the lead page, contact Enerflo support to have the lead re-mapped to the V2 deal.