Chuncks do not charge for non-host players in LAN

I play with my sister in 1.13 and we decided to play snapshot 1.14. So I went through the world in snapshot (world optimization etc...) and some time later, it was impossible for her to do some chunks without it bugging. There's no way to go any further. It must disconnect and then reconnect to continue to move forward. It's a bug that only happens in 1.14 and had never happened in 1.13. The chuncks no longer charge about 300 blocks from the spawner's location. This bug is really wearing for her. She can't leave our base.