Module category always set to other

[photographyshop]

Hi all,

I am a developper new to prestashop. Following the starting guide for modules, I found out that the following line has no effect on the module which always end up on the module category "Other".

$this->tab = 'front_office_features';

I have tried different categories I found on preinstalled modules such as shipping_logistics and advertising_marketing, without success

I have of course tried reinstalling clearing the cache creating a brand new module with a different name.., without success.

I have also tried copying one of the exisiting modules and changing the name of the folder, the  php file and the class, and the new module also ended up in the category "other"

I am using prestahop 1.7.6.8

Thank you in advance for your help.