My horse can't be leashed (Unsolvable)

In an anarchy world I created on Bedrock Edition, I spawned in a horse and tamed him, gave him blue leather horse armor, gave him resistance and regeneration (both amplified 255) and named him "Beloved Horse".

Back then, I can leash him along with my friend to cross a river, but now it seems like he’s broken.

After trying out the stuff from here to a skeleton, I wanted to keep my horse still on a boat whilst I was on creative. However, the horse doesn’t seem to get in. Not a problem, right?

What about leashing to put him in a single spot with a fence, doesn’t work either, even in Survival.

Literally holding a leash, but it is the Ride button instead. What’s weirder is that when I spotted another horse, it is leashable.

Like I said before, I can’t go deeper because I can’t access the in-game code using my phone.

Now I tried the following to try and fix it:

1. Since my lead is given via command, I decided to hunt down a nearby Wandering Trader to get the lead from the llamas. Still doesn’t work.
2. I removed the saddle and horse armor on him. Still, a Ride button is the result.
3. I tried crouching, but just like any other tamed horse, an Open button would appear. (If you don’t know what it does, it brings you to the horse’s inventory.) From @Parkerdaboss216

Will be updated just in case to show if it doesn’t seem to work.

It’s as if leads don’t exist in his world. How can I fix this?

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Now sadly, I can’t seem to find my horse anymore. He likely despawned or got messed around with the commands making him lost. He didn’t die or whatsoever, he only despawned.

Due to this occurring, this question is no longer solvable. Sorry for the inconvenience.