We have a custom button On Account object to query and display all open cases, open oppprtunoties and files/attachments linked to the record .User who has access to the Account record is able to vie a file uploaded by another user in the standard related list but not on the custom VF page. I queried content documentlink for that specific file and I do see an entry with sharetype ‘v’. I tried to change it to ‘I’ in the developer console, didn’t help either . Am I missing anything ? 
Thanks

We have a custom object called Feedback that has lookups to both Contacts and Opportunities. Feedback records are created from Opportunities using a custom button URL hack.

The custom button populates the Opportunity lookup and Date fields on a new Feedback record but won't populate the Contact lookup.

The Contact entry should be coming from the custom lookup field on Opportunities called Primary Contact (which is auto-populated with the Primary Contact Role using flows).

My custom button URL is

/a0V/e? 
CF00N6E000000h3Cz={!Opportunity.Primary_Contact__c}
&CF00N6E000000h3Cz_lkid={!Opportunity.Primary_ContactId__c} 
&00N6E000000h2HU={!TODAY()} 
&CF00N6E000000h2ID={!Opportunity.Name} 
&CF00N6E000000h2ID_lkid={!Opportunity.Id} 
&retURL=%2F{!Opportunity.Id}

Any help would be greatly appreciated!