Gregory's Server@haeckerfelix I have this *exact same problem with my Markus chair. For some time I had a heavy stranded copper wire connected to it that ran direct to my basement copper water supply pipe as ground. I also changed from a glass mat to a plastic mat and then to a 4x4ft OSB board underneath. Still didn't solve it completely. I have since changed to the Ikea JÄRVFJÄLLET chair and it happens much less frequently.
@haeckerfelix Interestingly, it only happens with one of my laptop/monitor pairs (I have 4 laptops each with a monitor on my desk) even after I swapped monitors so it must be a combination of the laptop, port, cable and wall mount that is susceptible to the field effect.