Aside from Politico's usual Left leaning slant on topics, this excerpt will be a clue as to why little has been do against the domestic terrorism and insurrection that is key agenda of Antifa;
"“Antifa is a real thing,” Wray added at that hearing. “It’s not a group or an organization, it’s a movement or an ideology, maybe one way of thinking of it, and we have quite a number — and I’ve said this consistently since my first time appearing before this committee — we have any number of properly predicated investigations into what we would describe as violent anarchist extremists. Some of those individuals self-identify with antifa.”
It may not be a dues paying, membership card carrying "organization" but it's clear that Antifa operates as an organization. Consistent actions via consistent training via publications that present t he procedures and methods to employ, the tactics to use, etc. - operating across the Country, across the word under the same banner/flag, dressed in what amounts to a uniform = Black Bloc*. This all shows common structure, standard procedures, etc. common to an "organization". There is a communications network that spreads information and contacts cadre' members to inform them on upcoming "events"(operations)~"protests".
I suspect that the foot dragging by FBI and DHS, etc. may be partly due to the involvement of relatives** to those employed in these agencies in the actions and key levels of planning, managing what Antifa and associates do.
* Term "Black Bloc" seems t be one Antifa coined, since planning communications prior to demonstrations will mention "Black Bloc".
** Children, grandchildren, nieces, nephews, siblings, etc.