My horses keep disappearing after a loading bar pops up on the screen

I was riding my horse in my survival world, and in the middle of my screen a loading bar shows up and all of my surroundings freeze. I waited a long time for it to unfreeze but nothing would happen, so I would exit the tab and open it back up again and my horse would be gone. So far this has happened to me twice and I had also lost everything that was on my horse, such as the saddle and armor. Lately my WiFi hasn’t been working that well, but I don’t know if it’s my WiFi connection or if it’s a bug. Please let me know what you think and I would appreciate it if you could fix it. Thank you.