bpost seems to agree with you indeed.

https://www.bpost.be/en/address-validation-tool
returns
"RUE DU COMMERCE 1  -  1400 NIVELLES"

It looks like a problem with the postcode areas: postcode 1402 spans here:
https://www.openstreetmap.org/relation/5724081

I bet the problem is more serious: the border between Nivelles and Thines (which should be the same as for the postcode) should be probably pushed somewhat to the east.