Error Access Select Quotes

Summary:

We are intermittently seeing users get errors on some quotes when opening them from Salesforce.com. When clicking on the quote number to open the error reads "Error: You have attempted an action that could not be completed. Please verify the service is available or contact your site administrator if the issue persists. Details: "You are not authorized to access this page"

Content (please ensure you mask any confidential information):

The error never seems to clear- even hours later. If they go into CPQ directly they can access the quote without issue. We confirmed in the steps that they have access etc… Does anyone have any idea what is causing this or how best to troubleshoot? It is very intermittent but I have now seen it with a handful over users over the past few weeks and just not sure where to look for the issue.