Hi,
Here you have removed the building tag from https://www.openstreetmap.org/way/1295828345, therefore it is no longer rendered as a building on the map. If the building is for indoor horse riding, see https://wiki.openstreetmap.org/wiki/Tag:building=riding_hall. The tag leisure=horse_riding should be used for the whole facility and not just for one building, example: https://www.openstreetmap.org/way/348819417, see https://wiki.openstreetmap.org/wiki/Tag:leisure=horse_riding