This isn't quite a bug, but I feel like it belongs here anyways.
Irelia has a certain combo that allows her to get 3 Qs off in quick succession.
>EE -> R -> Q -> Q -> Q
When the first Q is cast immediately after R, it will consume the mark from the E, letting the R apply its mark an instant after, which you can then use to Q twice more.
However, while spamming this in the practice tool, I've found it to be pretty unreliable. Sometimes I would consume the E mark, sometimes I would barely miss it and consume the R instead, leading to only 2 Qs in the combo.
I can't quite pinpoint why exactly I miss the mark. It doesn't seem to be range related (as long as you're in range for Q), as I've missed and hit the mark from both melee and range.
Anyways, I think it would benefit her QoL if it some under-the-hood tweaks were added to make this combo reliable. It seems to be a pretty important combo for Irelias to master (ICU and other Irelias are practicing it), but it feels terrible to seemingly randomly lose a Q.