X-H1 IBIS BUG: blurriness with certain shutter speeds

I've found a very serious problem with X-H1 IBIS causing blurry photos with a combination of certain shutter speeds.

I found that the photos I took from a trip yesterday were mostly blurry. I was using the 16-55mm f/2.8 red badge lens, and I know this lens is sharp when I was using it with my X-T2.

The first telling tale was the picture below:

The lower left hand corner outside of the green square was blurry

The picture is mostly sharp, except for the two blue square objects on the lower left hand corner outside of the green square. The green square is the focus point on this photo.

At first, I thought it was an AF issue, so I did a test by focusing on the same object with varying shutter speeds. Here are a series of photos ranging from 1/250th to 1/8000th shutter speeds at 100% crop. Again, the green square is where I placed the focus point of the camera.

1/250

1/320

1/400

1/500

1/640

1/800

1/1000

1/1250

1/1600

1/2000

1/2500

1/3200

1/4000

1/5000

1/6400

1/8000

I've tested 4 lenses so far, and I've found the 16-50mm f/2.8 red badge lens exhibiting this issue. Basically, anything from 1/250 to 1/1000, the photo will be blurry. The worst is at 1/500 shutter speed. It is repeatable. On the rare occasion, you'll get a tack sharp picture.

Even at 1/2000, the photo is still slightly blurry. It is only when you get up to 1/4000 then it starts to look really sharp again. The sharpest is when I shoot it at 1/8000 of a sec. Or if I shoot something at 1/25, when IBIS is working, the photo is sharp too. I haven't tested the speed between 1/25 to 1/200. But I'm guessing that it is blurry as soon as IBIS is not required for the focal length/shutter speed combination.

When I looked at other photos I took with the same lens from yesterday, some exhibiting alternating bands of sharpness and blurriness. Most photos were blurry at the focus point, but objects in front or behind can exhibit random sharpness or blurriness.

I've tested the same again with 56 f/1.2, there appears to be no problem at all. I tested it with 35 f/2. I think it may have exhibit a slight sharpness issue with IBIS, but it is probably very mild. Photos I took from yesterday with 10-24 appear to be fine. It may still be somewhat affected, I'm not sure.

Unfortunately, I've sold my X-T2, so I can't test this on a non-IBIS body. I'll have to borrow the X-T20 from my brother over the weekend to compare.

The bad news is that it occurs whether you have IBIS ON or OFF.  It also doesn't matter whether I use electronic shutter or mechanical shutter or whether electronic first curtain is involved.

Fuji need to fix this problem soon in the firmware soon.

PS - I'm using fw 1.01, but I recall seeing similar issue with this lens even on fw 1.00, and I wasn't too sure back then what was causing the blurriness issue. Now I know why.