Leads fail yet still show as attached

Sorry if this is a duplicate. I found it difficult finding the same issue.

• Lead fails as if entity is not attached yet the lead shows as attached and is not in inventory.

• Tested on a boat, destroying the boat did not drop the failed lead

• The failed lead cannot be attached to a fence or be unattached from the entity.

• The failed lead may "drop" if another lead fails in the same way as above on the same entity. Yet the failed lead that shows as attached will not drop if the entity is destroyed.

Trying to get 3 ocelots home from a jungle over 10,000 blocks away, I attach a lead to a boat and get 2 of the cats in it. I got myself and the other cat into another boat and began to boat away. However, the leashed boat would not move. I tried pulling it from land. I could not detach the lead and I could not attache it to a fence post. So, I broke the boat. Breaking the boat did not drop the lead. I attached my other lead to an empty boat and tried pulling it from land. It worked. So I loaded up the boats and set off.

I stopped for the night, slept, and set off again. The boat would not move. Going back to the boat, I noticed a lead floating in the water next to it. The first Lead?. I break the boat, again, and the boat did not drop the attached lead. I still have 1 of 2 leads. I repeat the attach and loading and set off home.

This happened again while bring small slimes home using 2 boats. I didn't notice the towed boat stop, the last time, and I lost it.

This happened again while leading a llama. I leashed a llama that wasn't far from home and began walking around searching for others. Night was coming, so I gave up with only 1 extra llama following. At one point I turned back and noticed the lead stretched way out, and the llama was "wandering". I went back and and tried to detach the lead but couldn't. I attach a second lead and the llama would not follow. So I stretched the leads until they broke. Only 1 lead dropped. Down a lead, I reattach a lead to the llama and took the llamas home. 

I have not wanted to kill the llama to see if the first lead pops out.