Hi Jonathan,
Greetings from Syncfusion support
By default, the lazy load grouping allows you to load grouped records to the Grid through the on-demand concept. So, you can use this feature to load a huge amount of grouped data to the Grid without any performance degradation.
When you enable this feature, the Grid will render only the initial level caption rows in the collapsed state at grouping. The child rows of each caption will be fetched from the server and render in the Grid when you expand the caption row. The fetching child records count will be implicitly determined by the content area occupying rows count. So, if the child records exceed the count, then the Grid will request the server again to fetch the next block of child records on scrolling.
So, we would like to let you know that group expandAll() support is not available when lazyLoading is enabled in the Grid. This is because only the current page row elements will be rendered in the DOM and so the entire data row elements cannot be accessed there for performing expand all action.
The caption row expand/collapse state will be persisted on paging and Grid pages count will be determined based on the caption rows count instead of the child rows.
Please get back to us, if you need any further assistance.
Regards,
Rajapandi R
