Apparently all the +one handed % enchants do not work on daggers. They do NOT increase dagger damage even though dagger is one-handed.

Is this intentional or is this a bug?

Bethesda, any idea on this?

(or was someone able to fix it?)

They do increase. Sometimes a bug is triggered where they don't. This is a bug and hopefully will be fixed.

They do? The enchants? Have you tried them?

So do you actually mean that sometimes it works and sometimes it doesn't?