Pictures (thanks to Tempax on r/SkarnerMains): https://imgur.com/a/0Z0Ad
After you flash with Hexflash in your runes, your flash (or more specifically, the key your flash in on) is disabled for the rest of the game and is greyed out. You can't cast any summoner spells on that key for the rest of the game.
Hmm...this happened to me as well a few times. It's not as simple as just flashing though, I've flashed plenty of times with it without having problems.
Do you know what else you were doing before it happened?
Alright, so I tested quite a few interactions. The bug occurs when I:
-Prepped my flash before ulting someone. -Flash and then ult someone, without prepping flash beforehand.
The bug does NOT occur when I:
-Hexflash before ulting someone. -Ulting someone while Hexflash is up. -Ulting someone when Hexflash is on cooldown. -Ulting someone right after using Hexflash. -Using chilling smite on someone while Hexflashing, or chilling smiting them after I Hexflash or flash. -Flashing before smiting, auto-attacking, Q'ing, or E'ing anyone.
All tests were performed being level 18 with all abilities leveled up, with the No Cooldowns tool being disabled. My rune path for all tests was I111 and S31.
