Sample V² data of PDS 456 on 2018-08-27 before (top) and after (bottom) selecting data with a group delay of < 3 μm. Without the data selection, the averaged visibility squared data are ≲0.65. There is also a trend that the visibility squared increases as the Strehl ratio increases for each baseline. In contrast, the visibility squared reaches ≃0.7−0.8 after the data selection, with no clear trend with Strehl ratio.