No. they just didn't write complete masses; just individual sections here and there. The masses were functional not artistic expressions. That is why Machaut's mass was a departure from custom. I don't know the answer to your question, but many of the sections were anonymously written.
Here's more from Grove:
There are three main sources for the French repertory (ed. in PMFC, xxiii). The Apt choirbook (F-APT 16bis) of around 1400 contains ten Kyries, nine Glorias, ten Credos, four Sanctus and one Agnus, of which 21 have text only in the upper voices. The slightly earlier manuscript I-IV 115 has four Kyries, nine Glorias, ten Credos, two Sanctus and two motets on Ite missa est; 15 of these are in motet style. The manuscript E-Bc 853c-d, containing five Kyries, one Gloria, three Credos and one Sanctus, is one of 12 Ars Nova manuscript fragments known from the old Kingdom of Aragon, which bordered on Avignon: between them they contain some 40 Mass Ordinary movements, of which 23 are in discant style. Small though the French Mass repertory may be, it is very widely disseminated, with several works appearing in ten or more sources, often in substantially different versions. Composers can be named for less than a third of the repertory, but at least five of them can be associated with the Avignon curia: Perrinet, Tailhandier, Tapissier, Sortes and Peliso.
Of the mass music by Italian composers (mainly Glorias, Credos and Sanctus settings, ed. in PMFC, xii) only about a quarter shows pure Italian style: the rest is heavily influenced by the French tradition. The main named composers are Philippus de Caserta, who worked in Avignon, and Antonio Zacara da Teramo and Matteo da Perugia, both connected with the papal curia in Bologna. In the entirely anonymous English repertory from the early 14th century (ed. in PMFC, xvi) Credo settings are particularly rare. Most of the music is in simple homophonic style and perhaps derives from the growing custom of singing Marian votive masses. Special to the English repertory is the survival of Mass Proper settings.
While the manuscripts normally grouped settings of a particular text together, there are some examples of apparent cyclic grouping, though never more than one such group in any single manuscript. The TOURNAI MASS (B-Tc 476, ed. in PMFC, i; also ed. J. Dumoulin and others, Tournai 1988), considered the earliest, has six Ordinary movements, of which the last is a motet in Ars Nova style, Se grasse/Ite, missa est/Cum venerint (known also from I-IV 115 and from the index of F-Pn n.a.fr.23190; the Credo has three further sources, two of them in earlier notation and of Spanish origin, and the Gloria has a further source in F-CA 1328 (n), no.2). Only the Kyrie, Sanctus and Agnus are unique, all in Franconian notation. There is no apparent musical connection between the six movements apart from their being all in three voices and all in simultaneous style apart from the concluding motet (which shares its tenor with a motet by Marchetto da Padova).
The four-voice Messe de Nostre Dame of Guillaume de Machaut, composed perhaps in the early 1360s for Reims Cathedral, is more unified and is important as the earliest such cycle conceived as a unit by a single composer. Machaut may have known some of the Tournai cycle, since his Gloria and Credo have similar textless musical interludes and share other features; they are in simultaneous style and end with a long melismatic Amen. The other four movements of Machaut’s mass are in the manner of motets, but all voices carry the same mass text. The tenor of the Kyrie is based on Vatican Kyrie IV; the Sanctus and Agnus correspond to Vatican Mass XVII; and the Ite is on Sanctus VIII. The Gloria and Credo have no apparent chant basis, though they are stylistically related to one another.