Thank you for clarifying the scenario.
After additional testing, I can confirm that this is currently a limitation, as the Grid does not officially support flex due to specifics in its rendering.
I understand this is not the best result, but currently, if the window is minimised the scrollbar will not be fully visible.
Apologies for the inconvenience this may cause you.
Also, in my previous response, I mentioned that in the first example the Grid is not scrollable because the scrolling functionality was not working and I was not able to scroll it:
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