Hi,
You have retagged https://www.openstreetmap.org/way/1210428367 from building=yes to leisure=horse_riding. But this object seems to be a building and is too small for a horse riding centre. Every building should have a building=* tag, otherwise it is not renderd as a building. The tag leisure=horse_riding is not for buildings, it is for complete riding centres (which may cointain some buildings, arenas and other things). Compare OSM wiki.
Good examples:
https://www.openstreetmap.org/way/494425529#map=18/46.118112/14.575688&layers=P
https://www.openstreetmap.org/node/12184697658#map=19/46.170882/14.606235&layers=P