As suggested I've upgraded to the SLESA-U7 interface in combination with the ESA PRO software to overcome the basic ESA software's limitations. In general I am very, very pleased with ESA PRO (congratulations!) but there are still some major bugs. Here are two of them:
(1) Whenever I save the file I am working on it is not possible anymore to "live" playback the scene. I have to quit ESA PRO, re-launch and then play it again.
(2) When using gradients in a scene it randomly re-sets the position of the first gradient to 0.00s. No matter what I do, whenever I set the first gradient point to e.g. 0.16s AND save it, after quitting the application and re-launching the file it moves the first gradient point (the upside-down triangle) to 0.00s.