(… or skilllag?)

Today I was in a group with 5 people being the only healer. When I was using my hots I noticed they didn’t go to the right person. They went to my previous target (if i targeted a freep, heals went to myself). This always happened to my first hot. After a while i decided to use my fell restoration skill first instead of my hot. This skill went again to my previous target. Several people died because of this annoying 'feature'

Im not sure why that kept happening. Is it because i swap targets too fast (I debuff the TA and use F to target the person being focused) , is it a bug or is it just server/skill/... another sort of lag?

PS: it wasn’t the first time this happened to me.