[BUG] GroupedVirtuoso increaseViewportBy top not increasing rendered items beyond current group

[sterlingwalsh]

Describe the bug

In a standard Virtuoso component, using increaseViewportBy renders additional items above the viewport. In GroupedVirtuoso, the additional items rendered stops at the beginning of the current group as rendered at the top of the viewport

Reproduction

https://codesandbox.io/p/sandbox/km9gvl

To Reproduce

Steps to reproduce the behavior:
In sandbox above, 4 buttons provided setting both virtuoso components (each with 10000 items) to the same scroll position and rendering the visible items as per the example in virtuoso docs. Large discrepancy in the starting rendered position, but expected discrepancy in ending position (as a result of group headers)

Expected behavior

as per the documentation https://virtuoso.dev/virtuoso-api/interfaces/GroupedVirtuosoProps/#increaseviewportby GroupedVirtuoso should pre-render items above the viewport corresponding to the provided size, not just the previous group

Screenshots

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Desktop (please complete the following information):

• OS: Mac Sequoia.
• Browser Chrome (latest)

Additional context
Add any other context about the problem here.

[petyosi]

The sandbox above must be private (quite an annoying default setting of codesandbox, I've done this as well).

[sterlingwalsh]

The sandbox above must be private (quite an annoying default setting of codesandbox, I've done this as well).

yep, thats definitely a dumb setting (but I guess it really depends on the intended use of that sandbox at the time. o well). Updated, signed out myself and verified access