Hi,
these four objects are buildings and you have retagged them to riding centres, the iD editir has removed building=yes and added leisure=horse_riding. Therefore they are no longer rendered as buildings on the map. I would recommend to undo this because a) every building should have a building tag. b) the tag leisure=horse_riding is not meant to be used for buildings but for complete riding centres and c) there should be only one OSM object with tag leisure=horse_riding for every riding centre (which in your case is https://www.openstreetmap.org/node/11414709495). For different types of buildings there are different building tags available, e.g. building=stable, building=riding_hall, building=barn, building=roof etc.

Related links:
https://wiki.openstreetmap.org/wiki/FR:Tag:leisure=horse_riding
https://wiki.openstreetmap.org/wiki/FR:Tag:building=stable
https://wiki.openstreetmap.org/wiki/FR:Tag:building=barn
https://wiki.openstreetmap.org/wiki/FR:Tag:building=riding_hall
https://wiki.openstreetmap.org/wiki/FR:Tag:building=roof