when testing a level, this happened...



when i crossed a certain point, some tiles (i believe one tile) just disappeared (became invisible) from the screen leaving a blank hole, as if it was triggered or so, only it reappeared after crossing another point - very weird, and it happened thru the whole level



i think this started happening when i had altered the tileset a bit and rebuilt it (not touching any used tiles tho)



i fixed the problem by just putting the same tile on the sprite layer again



now anyone know why it happened?