Had this issue on my realms server in the past affecting all kind of mobs. Yesterday I had a horse disappear on my Bedrock 1.20.1 Realms server. Leash still attached to the front of my house, no horse around.
what you were doing leading up to the mobs disappearing: Moving items from my old house to a new tree house;
single vs. multiplayer, local vs server/realm: Bedrock 1.20.1 Realms server;
how far you traveled: ~ 150 blocks distance;
how long the current or previous play session lasted: Probably more than an hour;
whether the despawns were near a player spawn point or if you had changed your player spawn point during the session: I had a new spawn on the tree and have probably slept on both places during moving, so yes to spawn change;
if you experienced lag or anything else abnormal: nothing abnormal.
knandobs
Had this issue on my realms server in the past affecting all kind of mobs. Yesterday I had a horse disappear on my Bedrock 1.20.1 Realms server. Leash still attached to the front of my house, no horse around.
what you were doing leading up to the mobs disappearing: Moving items from my old house to a new tree house;
single vs. multiplayer, local vs server/realm: Bedrock 1.20.1 Realms server;
how far you traveled: ~ 150 blocks distance;
how long the current or previous play session lasted: Probably more than an hour;
whether the despawns were near a player spawn point or if you had changed your player spawn point during the session: I had a new spawn on the tree and have probably slept on both places during moving, so yes to spawn change;
if you experienced lag or anything else abnormal: nothing abnormal.