ToME: the Tales of Maj'Eyal

So I have this weird bug that I see particularly often with Soul Rot and Drain (though I presume it can appear with any projectile, it's just these appear most often for me). The enemy activates the talent and it appears in the log, but the projectile doesn't appear on screen until the turn after. Not even on the caster (which is normally when I like to shoot down said projectile).

I presume this is because I have 57% slow projectiles and a global speed of 161%. As this never happened to me before since I never achieved these levels before.