A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Dear Mitchell,
Good day! Thank you for posting your query in our community.
Based on your description, when a user try to access the shared list, an error pops up. To check whether the problem is related to the specific account, please let the user switch to different browsers to see the result.
If the problem happens on different browsers, we assume the problem maybe relate to the backend and specific accounts, more resources need to be involved on the issue in your environment. I suggest you follow the steps in the article to open a ticket, this is a most efficient way to fix the issue in your environment. The engineers in related team have higher permission and more resource than us to help check it from background and collect the log remotely. This is also the most efficient way in handling this kind of issue.
Appreciate your understanding.
Sincerely,
Jazlyn | Microsoft Community Moderator