As far as I can tell there are no ATCOs on strike in FRA.
About 200 ground-staff are on strike including apron controllers and follow-me drivers. The media has difficulty telling which end of the airport is the runway, so this level of subtelty is bound to be beyond them and most of the general public. In common with most recent strikes these ground staff are being villified by an envious public and there is a one-sided media frenzy over the levels of reward and increase demanded. What is not being reported is that insufficient staffing requires too much overtime (does this sound familliar?) and that after talks broke down both sides agreed to independent mediation but the result was ignored by FRAport leaving the union with no further recourse, but to strike.
disclaimer - I have no first-hand knowlege of the situation and the above is based solely on what I have seen on-line elsewhere