Issue with Spellthief's Edge Proc

I've noticed that ever since the recent changes to the starting support items champs with DoT abilities don't proc Spellthief's edge multiple times.

Example: Morgana's pool or Malz's Maleficent Visions. It's my understanding that if a proc is available and a champ is damaged by a spell then the proc should trigger. But I have noticed that both these abilities only proc ST's Edge once, even if I have all three charges.

Can anyone else confirm this? And whether it used to be able to proc multiple times of DoT abilities?