Graphic Problems with iMac 27" 5k Retina and Cubase 8.5

Dear all,

I´m facing a serious issue with graphics on a brand new iMac 27" 5k Retina from Late 2015, which I just bought recently. The configuration is i7 with 4.0 GHz and 24 GB of Ram, AMD Radeon R9 M390 2GB.

I just uploaded a video of the problem to Youtube, which you can find here: https://youtu.be/q5YM-hhicrY

The project shown here has 140 tracks in total. Music is running fine, without any dropouts or CPU spikes, via Focusrite PCIe Dante card in an external thunderbolt enclosure from Sonnet (Echo Express SE II). No matter where the project is played back from, whether from the internal disk, an external SSD connected by USB 3.0 or even a high speed m.2 pcie ssd, located in the sonnet thunderbolt enclosure together with the soundcard, it´s always the same issue with stucking graphics.

I think for an actual hardware like this, this is neither normal nor acceptable…

Any ideas are highly appreciated ! - Maybe there are some of you, facing the same issue ? - Just leave me a comment here !

Thanks a lot for your precious help already in advance !

No that shouldn’t happen.
Does it only occur when Cubase is running?
If it does, does it only affect Cubase windows or does everything freeze up?
(to test, play a video file in a media player and watch that while Cubase runs in the background.)

Thanks for your answer - really appreciated. I will test this tonight, once I´m home again and will keep you updated here.

So, I tested. The problem is obviously coming from Cubase only, as it happens everytime, the moving position line in the middle is changing the page in the arranger window. If you turn it of, that the arrangement window is not following the actual position, the error does not appear and it´s working fluently.

Interesting, never heard of that before.
Does it also happen in a new, empty project?

Sorry for being late with my answer, but no, it happens only if your projects start to become massive, like bigger than 40-50 tracks…