Can't filter activities subcategorie "other" in "other".

That's not going to add the option in the interface.

Other is also a subcategorie of other. 

Where do you find Other as a subcategory of Other? I can't see that in the web interface or in the app.

It is probably easier to use the name search to find them. Remember to name them Other or something that makes them different from the other Other subtypes.

That's what I said, I can't find it and therefore can't filter for activities categorized as other, because I can filter for inline skating (Inline Skating is categorized as subtype Inline Skating and therefore not "other") in other, that's the issue. I can't filter for true other activities.

I only do one thing as other, they are all the same, the other others are classified as inline skating in other.

You wrote that :

KrapfenKringel said:

Other is also a subcategorie of other. 

But I can't find that Other is a subcategory of other. Other is a main type.

Still activities can be classified as other (without subtype if there isn't one) but not filtered out.

That is because Other is not a subtype of Other. To be able to filter you must use a subtype or set a distinct name. 

As others pointed out, Other is not a subcategory of Other. Activities which are categorized as Other have a main type of Other and no subcategory. So actual request here is to be able to filter activities with a given type (activityType = "Other") but no subcategory (activitySubType = not present / null / blank). Currently this isn't possible, but it doesn't seem unreasonable to me.

e.g. Maybe I want to see only Other activities with no subcategory, or only Running activities with no subcategory. Since the Garmin Connect activity type/subtype classification system allows activities to have no subtype, seems reasonable for users to want to be able to filter by activities with "no subtype".

Other is the correct designation as it is not listed in the available options.