Hi Everyone ! 
I already managed to tweak my code to bypass this issue (by coding an in-house use of N4BiasFieldCorrection) that I posted a while ago in General Discussion but since it looks like a major issue of dwibiascorrect ants to me (killing terminal/spyder) I thought I should make a reference to this issue in Development section too instead of General Discussion :
https://community.mrtrix.org/t/issue-dwibiascorrect-ants-crashing-terminal/8301
Regarding my in-house trick : I used a combination of mrinfo, dwiextract(of b=0), mrmath (avg of b=0), mrcalc(dividing image by N4map), mrcat, mrconvert (from mif to nii and vice versa) and of course N4BiasFieldCorrection from ANTs… to apply, in a similar fashion than what I could see from the error logs of dwibiascorrect, the N4 unbiasing.
Best Regards,
Arno ROSSEZ.