KNX Bus Rollershutter message delay

Tags: #<Tag:0x00007f616e18cf78> #<Tag:0x00007f616e18ce60>

I am trying to integrate KNX with my Openhab-2 installation and everything works fine.
But I am some kind of stuck in my understanding of how to control my rollershutters with percentage.

I mean I can fully open and close every rollershutter and it works fine but if I try to close one for lets say 50% it will start to close but stops just before it is fully closed.

After using the ETS5 Bus-Monitor I can see that the messages about the current state of the shutter (7%, 14% and so on) are coming in with an delay of 3 seconds (Bus workload only 2%). I am able to see the message with the current position on the bus while the shutter is at 50% down which is in case of one window 15%.
If I then tell openhab to close the shutter 15% it stops at 50%.

I am pretty sure that this is no Openhab-Issue. The software of my smart-home vendor has the same problem but do you have an idea how to correctly solve this problem?

If talking about roller shutters, is it like this one? https://www.rolladen-fenster-shop.de/media/Roma/Roma-farben-PVC-500.gif ?

Then please keep in mind, that the complete duration for opening/closing is divided in two parts:
Time1: time from “maximum open” (this is upper limit stop) to “shutter touches the window sill”
Time2: time from “shutter touches the window sill” to “no light or ventilation slots” (this is lower limit stop)

So, duration is Time1 + Time2. There are some roller shutter actuators which provide a correction factor for this, but why?
As you want a specific position, there is no need to set the shutter to 50% for half closed shutter.