Methods hookHeader and hookActionFrontControllerSetMedia not executed in module

[darioscattolini]

I don't know if this has something to do with the problem I'm currently having, but this is how it started. Some days ago a client of mine somehow managed to delete the Visitors group through the back office. This started to produce problems in modules relying on the existence of that group, so yesterday I restored all data relating to that group using a database backup.

After that restoration the search module of my client's website (Leo Product Search) started to look weird. I found out the page doesn't load the module's css and js files for the front office anymore. The searchbox looks awful and ajax features don't work, but search is performed correctly, so it's only a problem related to the module's assets.

I tried to make the hookHeader method in the module echo random strings but it didn't print anything at all (I tried this in the same method of other modules and it worked). So the problem is not related to the code inside the method (besides, it had always worked fine), since for some reason the hook method is not called at all. I rewrote the method as hookActionFrontControllerSetMedia, it worked fine on a local PrestaShop installation, but on my client's website it was not executed either. Naturally, I made sure the module was registered in the appropriate hook before testing.

Any ideas on what the problem may be and how I can go on debugging it?