I implemented silentwhisperer's recent fish farm, and it works great. All caught items are automatically put into a double chest. If I fish a few times, I can open the chest to see what I caught. If I fish for several minutes, maybe five to ten, and open the chest, the chest "opens", but the chest/inventory modal never appears. Instead I just see a small loading animation. I can move around, but I can't interact with anything else (can't change the item I'm holding; can't toggle a trapdoor). I tried leaving the fish farm without opening the chest, but the same issue happened with the next chest I opened. I tried going into the Nether and back, but when I did that, the Overworld never loaded, and I was standing in void of stars.

The only way I've been able to get "unstuck" is to force-close the game and relaunch. After trying to close Minecraft for a few moments, the Switch tells me the game crashed. I can then relaunch and play normally.

I'm playing on Realms Plus. I've only noticed the issue when I'm the only player on the server, but I haven't tried when others are on.