I am using Extjs 7.1 Modern Framework, and I have and exactlly problem on grid scrollToRecord()

1 when the grid scroll to the bottom of the list,
and call scrollToRecord(),
for example scrollToRecord(theFirstRecord)
the list screen become empty,
until manually scroll the scrollbar.

2. when try to scroll to the record that far away from the current list itme,
it cannot go to the target record even call multiple time of scrollToRecord()

Thank you