The WoD Mythic heirloom trinkets do not scale properly all the way to 50 (or 49 if you want to be technical). They scale up to 44 and are eligible for the 44-49 upgrade, but applying them only wastes the item. Neither the level cap, nor the iLevel are increased, however the “maximum upgrade level” gold background kicks in.
Trinkets affected:
Orb of Voidsight
Purified Shard of the Third Moon
Infallible Tracking Charm
Judgment of the Naaru.
…And the strength one I don’t know the name of because it never dropped 
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Can confirm this is the case for me too. My WoD trinkets were already upgraded to 120 before the pre-patch and still have the 1/1 upgrade, but now are capped at level 44 which would have been 109 pre squish.
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this has been that way since the pre-patch went on ptr.
Yup, add me to the list of people who wasted gold on an ‘upgrade’ for one of these that currently does nothing…
Noticed this myself. These are my fav heirloom trinkets. Would like to see a fix for them asap.
Pretty frustrated that since Blizzard took away the built-in PVP trinket I now need to use my Inherited Insignia of the Horde BOA trinket, which is stuck at ilevel 44 while my other heirlooms continue to scale appropriately.
Upgraded my Gronntooth War Horn to 1/1 and noticed it didn’t get upgraded past 1-44. I have all the other trinkets and the 0/1 upgrades remain 1-44 as well.
I understand that GM’s won’t be able to compensate for for the loss of the casing or 5000g but don’t send me to Wowhead to read comments when I have already specifically mentioned that my other trinkets at 0/1 are the same as the 1/1 ones.
I experienced a similar issue, but with the standard heirlooms. Heirloom levels were not updating retroactively on heirlooms created before they were upgraded (ex: a FULLY upgraded heirloom would stay at level 39, and character was level 42). This may be an issue with heirlooms created during pre-patch. Level is correct when I create a new heirloom via heirloom tab.
Basically wasted gold on enchanting the bugged heirlooms. I even pulled the trigger and spent more gold on enchanting “fresh” heirlooms 
.