Drag & Drop issue while conversion from Storyline2 to Storyline 3

Hello,

I have a major issue in Storyline 3, when using file created in Storyline 2 and automatically converted into Storyline 3 (and creating SL2 backup)

In SL2, my Drag & Drop exercice was working properly, all items were dropped properly.

In SL3 (update 4: 3.4.15731.0) , looks like it is impossible to drop items on the expected place, they appear to be dropped more or less randomly below the expected target...I tried to have a look into the forum, I did not find any specific reason, do you have any idea?

Olivier