Hi @Feuerborn, Thomas,
I think that the group will be collapsing because the interactive sort will re-run the report and then report will re-rendered.
It is by design, temporarily we could not change it.
You may share your idea here, the product team will consider to add the feature.
For Suggestions/Other Ideas: Tell us how this impacts your business operations and how what you're asking for will enable/unblock your scenario.
Regards,
Zoe Hui
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