Database Role seemingly lost permission
So I am wondering how this might have been broken (SQLServer update?).


SQL Server update wont change any login / user or role permissions as part of update (installing CUs or SPs).

The permissions might have changed due to a possible database upgrade (your application version upgrade). Check your upgrade scripts.

To find out who changed the permissions, you need to have a server side trace running and collecting relevant information.


  how can I see what permissions have been granted to a role?


You can use this TSQL to check permissions granted to a role.