F1-F5 Skill while using a WvW Banner (e.g. Dragonbanner)

Lately i have been able to use F1-F5 skills on my Scrapper while using a Dragonbanner.
When i pick up the Banner the F-Skills arent usable, but after dismounting (while still using the banner ofc) sometimes they reappear.

I am not sure if it is a bug or a feature to be able to use the F-skills after dismounting - OR if it is a bug/feature that i can't use them when i pick up the banner.

I know in the past F-skills would not function while using a banner.
So please enlighten me - or fix it. the one or the other way.

Appreciate your time o7