Hello there!
I have started evaluating the latest beta version of the Grid (4.1.0-beta-2) and had to remove all my overrides which were using the getLWCElement() function because it no longer exists. One of those overrides was fixing a rather annoying issue with date picker's month and year editor alignment.
The problem was that the editors were incorrectly positioned which made them invisible to the user and thus impossible to operate. This was happening because the alignment routine was relying on the document's body height, which is always 0 in Lightning Experience.
Turns out, this issue is mostly resolved in the new version of the product. However, there are still instances when it occurs. For example, when the Grid's host component is placed below other components on the page and the user has to scroll down to reveal it. The attached animated screenshot illustrates the problem.
I did some quick debugging but unfortunately was unable to pinpoint the exact place where things start going wrong. From the screenshot it is apparent that it is related to the scroll offset. It seems like the editor is stopped as soon as it reaches the invisible bottom of the screen which has been shifted up.
Note the lower edge of buttons in the background. Here is this page in the initial scroll state, those buttons are nearly at the bottom of the screen. There is certainly a connection.
I can provide additional information upon request.
Thank you!
P.S.
Would be awesome if this was resolved in the final release.