Interval with count 77 disappears when scrolling to the right
I believe this interval is crossing a tile boundary and the tile it belongs to is being removed when the tile goes off screen.
Solution:
This interval should be present in both tiles and then deduplication / clipping can be used to prevent drawing the instance and label twice
Making intervals present in all tiles they cover will also handle the case when intervals span many tiles
Interval with count 77 disappears when scrolling to the right I believe this interval is crossing a tile boundary and the tile it belongs to is being removed when the tile goes off screen.
Solution:
Example link