I was playing with my friend on a server i was hosting localy. I died next to a nether portal and noticed that none of the items had appeared in the nether, but had disapeared from the overworld. My friend and I went on to testing the bug. The items disapeared even if the dimension was loaded and a chicken disapeared through it. The same bug also occurred in singleplayer. In both scenarios the wasportal in the overworld in a plains biome.

What I expected to happen was...:
I expected both the items and the chicken to appear at the linked portal, in the nether.

What actually happened was...:
Both the items and the chicken disapeared and was not found again, my friend report that the chicken appeared for a brief moment in the nether before it disapeared for good.

Steps to Reproduce:
1. Build a nether portal.
2. Go through the portal in order to load the nether.
3. Go back to the overworld.
4. Toss any item into the portal and watch it disapear.
5. Go through the portal and see that the item is not there.