Are you using the right test probe B?

Please check below two photos for test probe B

Please pay attention to Image 3, there are four red arrows facing the four right angles. Actually, image 3 shows the incorrect test probe, image 2 shows the correct test probe. In some special cases, such as the diameter of the hole is 12.6mm, the test probe in the case of bending, image 3 shows that the finger can not be entered, while image 2 can be.

Please check the drawing from IEC 61032.