This problem occurred immediately when upgrading to Spark 2, released in August 2014.
After contacting Arturia support several times without answer I finally got this message from them September 27 last year (2014)
"This is a known bug with the GUI, and we are working on IT.
Please accept all apologies for the temporary inconvenience caused.
Feel free to come back to me if still any problem or misunderstanding.
This was the first time Arturia admitted that it was problems with Spark 2. They also claimed that an update would be available soon that would fix this. Now six months later, this update still do not exist.
I must say that Arturias support department is really bad, and sometimes I start to question their intelligence. But even so, to make Spark work with the market leaders of DAW's should not ever take +6 months to solve!
All I can say is that if all of us users keep shaving their backs, demanding a solution, they ought to do something sometime.