Hmmm, I’m clueless. The only thing left is if you can share your model to check it out.
Ok thanks for your help
The model comes from solid edge, I’m going to see with the model maker if he can send me another step with other parameters export
Anyway, you have answered my question perfectly, I know I’m not missing out on any quick handling, and I thank you for that 
Sorry, it seems I can’t add more answers for today
You’re welcome! It was nice to talk to you.
Hope I helped you somehow anyway
can you go into wireframe mode ( Z to go into pie menu and then push mouse left side like in Gta V ) and select all faces ? My guess is that maybe there’s a face inside which might be breaking the reflection
Other things I can suggest is using weighted normals modifier which can help with bad shading or you can use auto smooth shading ( it should be in top 3 options in mouse right click menu when youre not in edit mode )
this issue has happend to me few times and most of the time the problem was the shading method
Sorry, I had to wait until the next day to give you news.
After testing the auto smooth shade which unfortunately gave a wave effect on the chrome reflection, and the other suggestions, I tried to convert the STEP file to obj and gltf with CAD software, and got the same result. The problem comes from the CAD file and this was confirmed by the modeler.
Fortunately, I was able to clean up the area with the Mesh / Clean up / Limited Dissolve tool and the result is satisfactory 
Thank you all for your reactivity and your suggestions
Have a nice weekend!
Glad you did it
Have a nice weekend!
A bit late…
sometimes it helps to clear the custom normals under Object → Data → Properties…
