Yes, you are correct. The global preserving of grid options include expression based settings like filtering, sorting, grouping, paging, etc. It can be helpful to preserve the Grouped by columns, then apply the expand/collapse state explicitly using manual script logic.
If you want this functionality built-in, you can add your ideas in our public feedback portal and our developers may consider implementing them for the future releases:
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Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items