Smartsheet Group Management not working

Hi, weve been using Smartsheet for a large portfolio and are using group management to avoid having to share the entire workspace to the people involved in the project delivery as we have confidential financial data that we do not want other organisations to see. It was working well until it is not recently. For some reason, people shared under the group management can no longer access the sheets/reports/dashboards shared to them with no work around identified at the moment, we wouldn't want to share the workspace to more than 1000 people. issue started like 2-3 weeks ago. any ideas whats happening?