Access Denied error to a page where user has "Read" permission

I've given a user "Read" permission to 3 pages on SharePoint 365 and "Contribute" permission to the lists on those pages. They are able to do all the things they're supposed to with the lists. The problem is when they click on the Navigation links to the left side, they're getting an "Access Denied - request access" page. However, if they click the "Back" button of the browser, the page loads fine. This is a current workaround but obviously not ideal. I've checked and checked all 3 page permissions and they've been given "Read" permission to the page. My question is, how do we get rid of the "Access Denied" error page? They've even sent a request and I've approved it for the pages.

Thanks in advance.