In my last ranked game I played Thresh
and ranked my E first. I do not know if this played into the bug. The Relic Sheild 
( and Taragon's
) passive would not proc. It ended up proc'ing twice at one point midway through the game, but then went back to not working. Also the help technical section of PVP.net contains erroneous information about submitting reports through PVP.net preferences.
[slayer-jinx-unamused]
Deep Terror Nami4 votesHey Elarnia,
Thresh is classified as a Ranged champion, and only Melee basic attacks can proc Relic Shield's execute damage. Last hitting any other way will still give the heal/gold share though, and charging up his E passive helps with that.
daemanic1 votesThresh is a ranged champion meaning IT DOESNT PROC
Elarnia1 votesThresh is a ranged champion meaning IT DOESNT PROC
But it DID proc. At least twice. But only during a short period in the game. Also it is in his recommended build tree provided by RIOT. So if the item does not work for him, they have done a terrible job with his tips in game. If this is not a bug they need to remove the item from his recommended items. I am not an expert at League by any means, but it was my understanding that was for tank supports, which is. This just means I won't be playing ranged tanks like as supports which is disappointing
[zombie-brand-clap] .
EndlessSorcerer1 voteshttp://leagueoflegends.wikia.com/wiki/Relic_Shield
Melee autoattacks execute minions below 200 - 285 (based on level) health.
Killing a minion by any means heals you and the nearest allied champion for 20 health and grants them kill gold.
Read the bolded text above.
The EXECUTE is melee-ony and will not proc on ranged autoattacks. This means that you don't get the bonus damage to help you last hit the minion and must kill it normally.
The GOLD-SHARING and HEAL will trigger when you kill a minion through any source of damage (including abilities, Sunfire Cape, Thornmail, etc).
The tooltip is extremely clear and does not need to be 'fixed'.
Elarnia1 votesThank you for the clarification. Apparently I am just that bad at League.
EndlessSorcerer1 votesHonestly, at this point I'm surprised they haven't stickied a PSA for this topic at the top of the Report a Bug section.
People have been falsely reporting this bug at least twice a week for the past couple years.