There is an issue where in if the viewer has a normal mode version of an item and is viewing the heroic version it will still show the normal mode TMB Tooltips only as it's cached locally because it's owned.

To fix this I had to change line 479 to be:
local itemID = tonumber (strmatch(itemLink,"item:(%d+):"))

This corrected the issue as it now updates to the itemID of the item that is being hovered over.

Hopefully someone can correct this who has access.