Can't put used chest on donkey or mule

To put a chest on a donkey, right click it like you are feeding it something. This is working as intended.

I don't know if I am using the Bedrock version of Minecraft, I bought it a few months ago off of the Microsoft Store and it's connected to XBox Live. But for some reason this action is not working. I can feed them hay bales and golden apples and carrots, but right clicking with the chests in hand just makes me ride them. Would it help if I attached my world file?

I was able to place a chest on a donkey about three seconds ago. Just right click. Athough:
If the donkey is not actually tamed (if you bred it or just found it) you cannot put chests on it. If little red hearts came out of them at some point or another, then chests should work fine. A world file shouldn't be necessary but you can totally put it up and maybe I can take a look. If you bought minecraft on the Windows store then it is definitely bedrock edition.

Note: I am not an admin or a mod

Crouch then use the left trigger.

I can't attach the world file because the file size limit is 10 MB. The file is just over 30 MB. I have a saddle on my mule and can control it, so I know it is tamed. My donkeys are tamed as well. Could it be a bug exclusive to my computer? Is there anywhere I can put the file so that you can access it?

Crouching and using the left trigger just hurts my mule lol.

At this point I am not sure what is happening.
Load up a new creative world
Spawn a donkey
Tame it (don't put a saddle on, I might know the problem.)
Then right click it with a chest

Try zipping the (first) world file:
Go to File Explorer
Find the world file
Right click it and hover over the "send to" button
Select the "compressed(zipped) file" option
This may all be happening because of a separate bug that lets you put saddles on before taming, but I won't know until I know whether your mule is actually tamed.

It will take me a minute to find the original world file but I spawned a mule in creative then tamed it. It let me put the chest on it. So it must be this bug you're talking about, but I don't know why it would prevent me from putting chests on the animals that are tamed and that I've never put saddles on.

Ok so I can't find the original world file, I must be blind and/or stupid, could you tell me where to go to find it? I exported the file from in the game and put it on my desktop but when I zipped it the zipped file was larger than the original file.

I'm having the same problem.
Win 10
Mincecraft:BE v1.2.13

I bred a mule, tamed it, put a saddle on it (definitely tamed - I can ride it around, make it jump, etc). Now I can't give it a chest. I've removed the saddle and tried again, but to no avail. In case it matters, I did stuff the thing full 'o wheat to make it grow faster.

I also did as requested above and used the seed to start a creative world - no issues. It's only in the survival world.
(on an possibly not-so-unrelated issue: slimes spawn readily in the creative world, but are infuriatingly rare in the survival one)

Also having the same issue, both on Windows 10 and Xbox (Bedrock) 1.2.13

Pure survival world on Realms. Never been set to creative (I earn achievements)

Tamed donkey, bred a and tamed mule, cannot put a chest on either. Chests on Llamas works okay.

Just tried an experiment. Made a new world in creative, made a bunch of donkeys and mules with spawn eggs. Could put chests on donkeys and mules. Changed to Survival, could also still put chests on donkeys and mules.

Also tried breeding a horse and donkey in survival mode (parents were tamed in creative mode) and could tame and put chests on it.

Perhaps it is a bug in wild spawned donkeys and mules vs ones made with spawn eggs? So far I can only reproduce on a pure survival world.

I've been trying this on a Realm that's always been set to survival mode, on both world-generated and bred donkeys, and it won't work. The method results in riding the donkey, instead of placing the chest on it. Tested on Windows 10, Android and Fire TV. Only got it to work on creative maps where the donkeys are spawned in with eggs.

As of version 1.4.0, the donkeys in the realm I mentioned earlier now have different results. The donkeys that were world generated now accept chests. Those that were bred do not. For these, the method now results in opening the donkey's inventory (for giving it a saddle)

I found a solution to this problem.
Simply use a clean chest (not used).

Sorry for my bad English.

Thanks for the extra information - if you place, break, and pick up a chest, then you can't equip a donkey with that chest. (Tested in 1.4.2.0)

As mentioned, a workaround for this is to either use a new chest, or to combine a chest with other chests first, then it can be used on a mount.

When you break a chest, large chest, or trapped chest, its NBT Damage value is incorrectly incremented, making it a "damaged chest".

When you stack a chest (including by picking up a chest item), it inherits the damage value from the stack. Thus, if you stack a newly crafted or undamaged chest onto a damaged chest, both will be damaged. Conversely, if you stack a damaged chest onto an undamaged one, the damage will be reset.

This issue also affects equipping a chest onto a llama. However, a damaged chest can still be used to craft a shulker box, trapped chest, or minecart with chest.

If you break a minecart with chest, it drops an undamaged chest.

This issue may have the same root cause as MCPE-32347, in which various kinds of items cannot be stacked in inventories. If those items are having their Damage values incremented, like the chest in this issue, that would make them unstackable with undamaged items (as well as with items having different Damage values). The bug would then be the same in both tickets: that under some circumstances the DV is being incremented for items that do not take damage.