Hello People, I have created a custom role and provided it view permission for items. I also elevated the service file permissions and made it execute script with that custom role. I am still getting this error: "You need the 'Lists -> Items' permission to access this page. Please contact your account administrator." Is there any reason this is happening?

Make an invalid cache validation, try on incognito and make sure you are elevating the permissions to the right service file. Try adding full or edit permission instead of view.