Players cannot equip Wolf Armor to their tame wolves on Realms Worlds that were loaded to the Realm Server before the 1.20.80 release.

Steps to Reproduce:
1. Have a pre-existing Realms world
2. Load the World and tame a Wolf or use an already tame Wolf (that you own).
3. Craft and/or have Wolf Armor in Inventory
4. After taming a Wolf, attempt to interact with the Wolf whilst holding the Wolf Armor Item

Observed Results: 
1. The tame Wolf will only sit/stand when being interacted with whilst holding the Wolf Armor Item

Expected Results: 
1. After interacting with a tame wolf whilst holding Wolf Armor, the Wolf should now be equipped with the Armor

Attachments: 
1. Test 1
"Wolf Armor Equip Test" on a Realms World that was active and loaded before the 1.20.80 release
2. Test 2
"Wolf Armor Equip Test" in a Local World that was created before the 1.20.80 release
3. Test 3
"Wolf Armor Equip Test" in a Local World freshly created after the 1.20.80 release
4. Test 4
"Wolf Armor Equip Test" in the same World created in Test 3 (above) but loaded onto a new Realm Server.
5. Test 5
"Wolf Armor Equip Test" on a different Realms World from Test 1, but also a World that was loaded and Active prior to the 1.20.80 release
6. Test 6
"Wolf Armor Equip Test" in the same World as Test 5, but as a Local World downloaded from the Realm Server. 
7. Test 7
"Wolf Armor Equip Test" in the same World as Test 5 & 6, but re-uploaded to the Realm Server. 
8. Download Error
I made an attempt to Download the World from the Realms Server that was used in Test 1 above but encountered an error, so I repeated the Testing in a different World on a Realms Server 

Notes: 
 
Test 1 - Carried out on a Realms Server in a World that was created before the 1.20.80 release. I expected to see the Wolf Armor be successfully equipped to a Tamed Wolf.
Test Failed 

Test 2 - Carried out in a Local World created before the 1.20.80 release. I expected to see the Wolf Armor be successfully equipped to a Tamed Wolf.Test Passed

Test 3 - Carried out in a newly created world after the 1.20.80 release.  I expected to see the Wolf Armor be successfully equipped to a Tamed Wolf.
Test Passed

Test 4 - Carried out in the same world as Test 3, but with the World now loaded onto a Realms Server. I expected to see the Wolf Armor be successfully equipped to a Tamed Wolf.
Test Passed

Test 5 -  Carried out on a Realms Server in a World created before the 1.20.80 release but different from the World used in Test 1. I expected to see the Wolf Armor be successfully equipped to a Tamed Wolf.
Test Failed 

Test 6 - Carried out in the same world as Test 5, but with the World now downloaded as a Local World. I expected to see the Wolf Armor be successfully equipped to a Tamed Wolf.
Test Passed

Test 7 - Carried out in the same world as Test 5 & 6, but with the World now loaded back onto a Realms Server. I expected to see the Wolf Armor be successfully equipped to a Tamed Wolf.
Test Passed

The issue only occurs on Realms Worlds created before the 1.20.80 date. Downloading the World and re-uploading it to the Realm appears to rectify the issue, if only as a jerry-rig option, until the bug has been fixed.

This bug appears to have been encountered here MCPE-180985 & here REALMS-11763

If the Dropbox links included above do not work, here is a link to a Google Drive Folder with the Files.