Faceted Search completely ignores some (random) subcategories

[TinoArts]

PrestaShop 1.7.5.0, Faceted Search v3.7.0

I have a Category filter widget with the depth of 1 set in Faceted Search module. It displays fine. It works fine for the most part. However, for some categories it just doesn't work at all. In the screenshot (the first one) I have selected ALL subcategories. The red ones are selected successfully, the grey ones just won't get selected at all. They are not added to the active filters. 

In another screenshot (the second one) you can see that all of those categories are enabled in Faceted search settings. There ARE in-stock and available products in those categories, so that is not the case. I've also tried disabling Faceted cache system, but no luck.

What could be the issue?

Thank you.

Edited March 2, 2021 by TinoArts (see edit history)

[TinoArts]

@caovillanueva I actually found the issue in the meantime, but forgot to update this thread. I also found a workaround, but not a real solution.

I've reported the issue on GitHub: https://github.com/PrestaShop/PrestaShop/issues/23815

It got closed, but not really resolved. 🙃

TLDR: Turned out it was the slash ("/") symbol (and sometimes hyphen ("-")) that caused issues. Once I renamed categories and changed these symbols, it works well.

Could you try, if this is the issue on your end as well?

Edited July 22, 2021 by TinoArts
typo (see edit history)