I read somewhere that the Jewish bishops were notably uninvited to the council.
My understanding, is that all 1,800 bishops were invited to the 'universal meeting' (technical term "ecumenical council") of the church in 325. Of that number, roughly 318 bishops are thought to have actually answered the summons, arriving with their respective retinue of deacons and lay advisors ('acolytes').
Apparently, attendant bishops came even from Britain and Sassanid Persia (beyond the confines of the Roman Empire) to 'argue their case'.
Having myself no prior knowledge of this 'non-invitation' of Jewish bishops, I conducted a search online and did find this from a book entitled,
Faith of the Ages: The Hebraic Roots of the Christian Faith (2012) by the American Pulitzer-prize winning historian Richard Rhoades, which reiterates this claim you've read elsewhere (see paragraph 3):
That could also explain the very important 'calendar' decision that was adopted in relation to the celebration of Easter at the Council:
First Council of Nicaea - Wikipedia
The feast of Easter is linked to the Jewish Passover and Feast of Unleavened Bread, as Christians believe that the crucifixion and resurrection of Jesus occurred at the time of those observances.
As early as Pope Sixtus I, some Christians had set Easter to a Sunday in the lunar month of Nisan. To determine which lunar month was to be designated as Nisan, Christians relied on the Jewish community. By the later 3rd century some Christians began to express dissatisfaction with what they took to be the disorderly state of the Jewish calendar. They argued that contemporary Jews were identifying the wrong lunar month as the month of Nisan, choosing a month whose 14th day fell before the spring equinox.[55]
Christians, these thinkers argued, should abandon the custom of relying on Jewish informants and instead do their own computations to determine which month should be styled Nisan, setting Easter within this independently computed, Christian Nisan, which would always locate the festival after the equinox. They justified this break with tradition by arguing that it was in fact the contemporary Jewish calendar that had broken with tradition by ignoring the equinox, and that in former times the 14th of Nisan had never preceded the equinox.[56] Others felt that the customary practice of reliance on the Jewish calendar should continue, even if the Jewish computations were in error from a Christian point of view.[57]
The controversy between those who argued for independent computations and those who argued for continued reliance on the Jewish calendar was formally resolved by the Council, which endorsed the independent procedure that had been in use for some time at Rome and Alexandria. Easter was henceforward to be a Sunday in a lunar month chosen according to Christian criteria—in effect, a Christian Nisan—not in the month of Nisan as defined by Jews.[6] Those who argued for continued reliance on the Jewish calendar (called "protopaschites" by later historians) were urged to come around to the majority position. That they did not all immediately do so is revealed by the existence of sermons,[58] canons,[59] and tracts[60] written against the protopaschite practice in the later 4th century.
However, that evidently did not 'extirpate' the problem - as the orthodox church of the time saw it - of Jewish believers in Jesus continuing to adhere to the law, for a number of centuries later at the
Second Council of Nicaea, we find this:
The Bishops at the Second Council of Nicaea: Canon 8 on the Treatment of Jews Converted to Christianity (787 CE)
The Bishops at the Second Council of Nicaea: Canon 8 on the Treatment of Jews Converted to Christianity (787 CE)
Since some of those who come from the religion of the Hebrews mistakenly think to make a mockery of Christ who is God, pretending to become Christians, but denying Christ in private by both secretly continuing to observe the Sabbath and maintaining other Jewish practices, we decree that they shall not be received to communion or at prayer or into the church, but rather let them openly be Hebrews according to their own religion; they should not baptize their children or buy, or enter into possession of, a slave
The decree is, of course, referring to Jewish followers of Jesus who, at that time, evidently still existed and kept Torah observance somewhere in the Eastern Roman Empire.
In the long-run, it could arguably be said to have been of benefit to both faiths that strict borderlines were drawn at the ecumenical councils beginning with Nicaea in 325 CE, between "Jew" and "Christian".
For those in that sort of 'precarious' bardo-realm in the middle, many of whom were still attached to synagogues in the fourth century according to St. Epiphanius in his
Panarion, the imposition of Nicene orthodoxy was most unfortunate. As he informs us, writing in 374–377, some fifty years after the Nicene council:
The Panarion of Ephiphanius of Salamis
We learn from St. Jerome (345-420) in a letter to St. Augustine, that these 'Nazarenes' - whom St. Epiphanius in the above said were neither in accord with Christians or Jews, neither 'fish nor fowl' and about whom he had no idea if they regarded Jesus as just a "
mere man" or if they affirmed the Virgin Birth - were still extant in fourth century synagogues even though the Rabbis ('Pharisees' as he calls them) also regarded them as
minim (heretics).
He calls them Ebionites:
CHURCH FATHERS: Letter 75 (Augustine) or 112 (Jerome)
What shall I say of the Ebionites who pretend to be Christians? To-day there still exists among the Jews in all the synagogues of the East a heresy which is called that of the Minæans [Minim], and which is still condemned by the Pharisees; [its followers] are ordinarily called 'Nasarenes'; they believe that Christ, the son of God...to be the one who suffered under Pontius Pilate and ascended to heaven, and in whom we also believe. But while they pretend to be both Jews and Christians, they are neither.
But,
c'est la vie.