Lily H

Don't know why this occurs, but I would suggest hopping into creative mode, digging a couple blocks down, placing a hopper connected to a chest, then using water to get your items into the hopper to at least get them back.

I wouldn't consider this a bug, just a difference in versions. Minecraft Java and Minecraft Bedrock are technically considered two different games, so the coding might just be different for each version.

Now, I don't know much, but from what I've seen in other games and different Minecraft updates, something may have occurred where two actions relating to your fox happened either very close together or at exactly the same time, confusing the game into thinking the fox was doing something it wasn't. Depending on what that thing was, the code may have been written in such a way where the thing the game thinks the fox is doing isn't allowed to put the fox in a boat or on a lead, so it won't let you do that when you should be able to. 

This is just speculation, but it seems reasonable for this to be the case.

This is most likely because each individual particle counts as a sprite, and the more sprites there are, the laggier the game gets. If you were spamming them, then yes, the game would naturally lag. Same with spawning lots of mobs, it lags the game quite a lot.

Seems like you play on Switch? There's no need to double-tap, just hold down the left joystick when you want to sprint, that should do it! The only other thing I can think of is if you have something stuck under the joystick or there's something sticky in/on it.

See, I've experienced this, and it is quite hard to reproduce. It seems to be random, and that's why it never gets payed attention to. I just reported a door disappearing in creative mode, and I have absolutely no idea how to reproduce it.

I've seen this with zombies as well, on Switch.

Can confirm this happens on Switch as well

I can confirm this on Switch!