Decription: Sindragosa's debuff she gives - Unchained magic [Inflicts an arcane malediction on the target, causing any spells cast to result in a backlash of Arcane power after 5 sec. Multiple spellcasts by the afflicted target will intensify the backlash.] applies its aura called Instability[Using magic while afflicted with Unchained Magic will build up unstable energy, dealing 862 Arcane damage to the caster per spell cast, 5 sec after spellcasting ends.] on instant cast spells but when you cast a non instant spell(for example Shadow bolt) the Instability stack is procced on hit and not on release. I have seen this bug on other private servers and I have done the same report already(will not mention any names here).

How it should work: Instability stacks should be procced only from casted spells and not on hits or channeling spells such as penance. This is literaly what the spell description says - [Inflicts an arcane malediction on the target, (CAUSING ANY SPELLS CAST) to result in a backlash of Arcane power after 5 sec. Multiple spellcasts by the afflicted target will intensify the backlash.]

Source (you should point out proofs of your report, please give us some source): Here is my source. The video is from 2010 march 3(it is in the description of the video although the video is posted 2012 it's from retail. There are plenty of videos on youtube showing how unchained magic is supposed to work and since the video shows it clearly I decided not to post any more videos.
Here it is: https://www.youtube.com/watch?v=B_HZPgLVBGE - Affliction warlock taking instability stacks from casted dots and from casted Shadow bolt and haunt.
Thanks for the attention!