Beds don't save spawnpoints on server

I'm running a SMP vanilla server with 10 players or so. Besides the fact that the server is getting a lot of lag spikes (dedicated server: i7 4790k, 6GB RAM allocated, tested on both versions 1.14 and 1.14.1 snapshot) which isn't the issue here, I would like to mention that when all players successfully slept in their beds, when any player dies, they won't get respawned at the bed spawnpoint, but at the world spawnpoint. (beds aren't destroyed, they are placed in a large place). They will eventually get the message "bed is missing...", which isn't true.

One more thing to mention is that this WORKS as expected in singleplayer.