Spawning dolphins produced major crash

After spawning dolphins in creative mode, all entities freezed, no fish, turtles or dolphins moved. Commands don't work either. You can see the animals but can go through them. trying to save and quit doesn`t work either, system doesn't shut.

no mods installed.

log report:

[19:52:40] [Render thread/INFO]: Setting user: Manolita131
[19:52:45] [Render thread/INFO]: Backend library: LWJGL version 3.2.1 build 12
[19:52:48] [Render thread/INFO]: Reloading ResourceManager: Default
[19:53:06] [Render thread/INFO]: OpenAL initialized.
[19:53:06] [Render thread/INFO]: Sound engine started
[19:53:06] [Render thread/INFO]: Created: 1024x1024x4 minecraft:textures/atlas/blocks.png-atlas
[19:53:06] [Render thread/INFO]: Created: 256x128x4 minecraft:textures/atlas/signs.png-atlas
[19:53:06] [Render thread/INFO]: Created: 1024x512x4 minecraft:textures/atlas/banner_patterns.png-atlas
[19:53:06] [Render thread/INFO]: Created: 1024x512x4 minecraft:textures/atlas/shield_patterns.png-atlas
[19:53:06] [Render thread/INFO]: Created: 256x256x4 minecraft:textures/atlas/chest.png-atlas
[19:53:06] [Render thread/INFO]: Created: 512x256x4 minecraft:textures/atlas/beds.png-atlas
[19:53:06] [Render thread/INFO]: Created: 512x256x4 minecraft:textures/atlas/shulker_boxes.png-atlas
[19:53:07] [Render thread/INFO]: Created: 256x256x0 minecraft:textures/atlas/particles.png-atlas
[19:53:07] [Render thread/INFO]: Created: 256x256x0 minecraft:textures/atlas/paintings.png-atlas
[19:53:07] [Render thread/INFO]: Created: 256x128x0 minecraft:textures/atlas/mob_effects.png-atlas
[19:53:12] [Render thread/WARN]: Ambiguity between arguments [teleport, destination] and [teleport, targets] with inputs: [Player, 0123, @e, dd12be42-52a9-4a91-a8a1-11c01849e498]
[19:53:12] [Render thread/WARN]: Ambiguity between arguments [teleport, location] and [teleport, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[19:53:12] [Render thread/WARN]: Ambiguity between arguments [teleport, location] and [teleport, targets] with inputs: [0.1 -0.5 .9, 0 0 0]
[19:53:12] [Render thread/WARN]: Ambiguity between arguments [teleport, targets] and [teleport, destination] with inputs: [Player, 0123, dd12be42-52a9-4a91-a8a1-11c01849e498]
[19:53:12] [Render thread/WARN]: Ambiguity between arguments [teleport, targets, location] and [teleport, targets, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[19:53:12] [Server thread/INFO]: Starting integrated minecraft server version 1.15.2
[19:53:12] [Server thread/INFO]: Generating keypair
[19:53:12] [Server thread/INFO]: Reloading ResourceManager: Default
[19:53:13] [Server thread/INFO]: Loaded 6 recipes
[19:53:13] [Server thread/INFO]: Loaded 825 advancements
[19:53:13] [Server thread/INFO]: Preparing start region for dimension minecraft:overworld
[19:53:15] [Render thread/INFO]: Preparando área de aparición: 0%
[19:53:15] [Render thread/INFO]: Preparando área de aparición: 0%
[19:53:15] [Render thread/INFO]: Preparando área de aparición: 0%
[19:53:15] [Render thread/INFO]: Preparando área de aparición: 0%
[19:53:15] [Render thread/INFO]: Preparando área de aparición: 99%
[19:53:16] [Render thread/INFO]: Time elapsed: 2416 ms
[19:53:16] [Server thread/INFO]: Changing view distance to 11, from 10
[19:53:17] [Server thread/INFO]: Manolita131[local:E:fa650d71] logged in with entity id 99 at (2765.462967688689, 64.31610926689868, -1027.2362551622891)
[19:53:17] [Server thread/INFO]: Manolita131 se unió a la partida
[19:53:18] [Render thread/INFO]: Loaded 415 advancements
[19:54:12] [Render thread/INFO]: [CHAT] No se encontraron entidades
[19:54:12] [Server thread/WARN]: Can't keep up! Is the server overloaded? Running 53253ms or 1065 ticks behind
[20:01:25] [Render thread/INFO]: Stopping!