That's what I thought at first, but it's happening each time I use a slow shutter speed on my tripod. I also tried during the same shoot to go from 1s to /250th of a second and that makes a huge difference.
I am at the moment struggling to shoot slower than 1/50th of a second on tripod.
Erik
Let me try to explain my thoughts regarding your described issue .
Might be that you have already checked all of them .
Your setup has actually three parts . Tripod with head , Lens , Camera .
Each of them could be a culprit .
Your tripod . Have you checked all joints and legs and tightened them properly ?
I never extend the legs fully , I always leave about 5cm in the thinner leg . That increases the stability a lot .
Are the rubber "shoes" and/or spikes tight ?
Have you checked all moveable parts of your head ?
Could you replace the tripod and/or head by an other setup ?
Have you tried to shoot with an other GFX lens ? Does the issue show as well ?
I dont know the GFX , never had one in my hands .
But the camera could also be a culprit . Shutter ? ? ?
Can you eventually replace the camera ? ? ?
You surely have other cameras . Have you tried any other camera combination ?