Hi @Sammy13 

Only Approver with Approver_user role can approve the request.

sn_request_approver_read is only for reading approval record.

I guess business stakeholder's role conflicting, that's why not working.  You can raise a case(Hi Ticket) to ServiceNow support for their assistance on this conflicting role.

Refer this KB and  ServiceNow documentation :

Employee to-dos approval roles 

KB2189226 Approvals visible to end user on Employee center