17th Century Particular Baptists did believe in an invisible church:
26.1 The catholic or universal church, which (with respect to the internal work of the Spirit and truth of grace) may be called invisible, consists of the whole number of the elect, that have been, are, or shall be gathered into one, under Christ, the head thereof; and is the spouse, the body, the fulness of him that filleth all in all.
The also believed in the necessity of the local (or visible) church:
26.5 In the execution of this power wherewith he is so intrusted, the Lord Jesus calleth out of the world unto himself, through the ministry of his word, by his Spirit, those that are given unto him by his Father, that they may walk before him in all the ways of obedience, which he prescribeth to them in his word. Those thus called, he commandeth to walk together in particular societies, or churches, for their mutual edification, and the due performance of that public worship, which he requireth of them in the world.
...and that the local church is to be constituted of professed believers:
26.6 The members of these churches are saints by calling, visibly manifesting and evidencing (in and by their profession and walking) their obedience unto that call of Christ; and do willingly consent to walk together, according to the appointment of Christ; giving up themselves to the Lord, and one to another, by the will of God, in professed subjection to the ordinances of the Gospel.
In the minds of Particular Baptists, the invisible church is simply the sum total of all believers throughout human history. It is nothingness than the whole body of Christ, from the first believer to the last.
I weigh in on this because Particular (Reformed) Baptists are sometimes accused of advocating an authority other than the local church. That is patently untrue.