This is happening to me as well. Logitech G500. First 2-3 days of playing the game were great, no problems whatsoever. Over the last 48 hours this issue has rapidly been getting worse and worse. At this point my necromancer is unplayable due to the issue and my main (ranger) seems to be approaching the same level of unplayability (how strange that it affects different characters to varying degrees, even with a different mouse). If this isn’t fixed or at the very least acknowledged I’m going to have to pursue a refund.
I don’t even mean that as a veiled threat, as I would love to continue playing this wonderful game … unfortunately I cannot do that and I can’t justify spending $60 on something I cannot use as intended. I do not have this issue in any other game.