He backed Andrei Șaguna's bid to set up the Romanian-centered Metropolis of Transylvania, becoming its suffragan bishop; during the Serb–Romanian church partition, he extended the Arad Bishopric south into the Banat.

In 1873, following Șaguna's death and the row between Romanian conservatives and liberals, and being the more neutral choice, he was elected Transylvanian Metropolitan.

Although already old and ailing, his resignation in 1879 was widely attributed to Hungarian intrigues, involving Kálmán Tisza, Ágoston Trefort, and Ivačković's eventual successor, German Anđelić.

He was the scion of a priestly family called Ivașcu, Iovașcu, Ivacicovici, Ivașcovici, Ivacicoviciu, Ivacskovics;,[1][2] from Goruia village in today's Caraș-Severin County, Romania.

In this ethnically diverse environment, he frequented Serb and Romanian Austrians, which were at the time united under a single Serbian Orthodox jurisdiction: the Metropolis of Karlovci.

[8] Researcher Cvetko Pavlović links Prokopije with the "Romanian rebel" clan Ivačković, who had settled in Montenegro Vilayet as Muslims.

[17] After attending gymnasium in Oradea and Novi Sad, Ivačković studied philosophy in Kesmark, theology in Vršac and law in Sárospatak.

The Serb hierarchy viewed this as a compromise move, the appointment of a fellow prelate who seemingly opposed Romanian nationalism.

[18] In 1855, he and Șaguna reputedly endorsed Nicolae Tincu-Velea as Archpriest of Caransebeș, but their favorite was rejected by Emilijan Kengelac, the Bishop of Vršac.

[19] In other aspects of his mission, Ivačković also adhered to the Austrian line, ordering in 1854 the destruction of church documents which showed trace of collaboration with the rebellious Hungarian State of 1849.

The latter agitated among the Serbs and Romanians, hoping to obtain their support for a break with Austria, and to this end held an illuminated procession outside the bishop's residence.

[44] In later years, abbot Iosif Goldiș accused Ivačković of simony, alleging that his election had been fixed by Babeș, his Arad protege.

He claims that several pro- and anti-Hungarian factions coalesced to prevent Bishop Miron being elected, and pushed Ivačković as a safe candidate.

[5][48] For part of his reign in Sibiu, Ivačković was attracted into disputes surrounding the Diocese of Bukovina—located in Cisleithania, and populated by Romanians, Ukrainians, and Rusyns.

In December 1873, Theophil Bendella, who vied for the office of Bukovina bishop and wanted to join it with the Transylvanian Metropolis, claimed that Ivačković supported him.

Following the death of Patriarch Samuilo Maširević in 1870, the liberal disciples of Svetozar Miletić began organizing and reforming the Serbian dioceses.

[55][4] Part of the message read: Several Romanian commentators see Ivačković's move to Karlovci as a sample of Orthodox cooperation—described by historian Teodor Păcățian as a "laudable" gesture.

[4] The Mocionis' paper Albina also commented favorably, noting that the Serb synod showed its "trust of the Romanians", as well as a "penchant for church solidarity.

[45] At the time, Gura Satului published what it claimed was a found text reflecting the real feelings of Romanian parishioners.

Criticizing Ivačković's choice and noting that he was a double-dealer, this piece also proclaimed: "We don't regret at all the loss of such a prelate, but quite the contrary, we rejoice having discarded a man of the past and an adversary of Romanian culture".

[56] The latter's conflict with the Hungarian Prime Minister, Kálmán Tisza, was only enhanced by the Great Eastern Crisis, which rekindled ethnic aspirations in the former Karlovci parishes.

[62] The final months of Patriarch Ivačković's reign saw Karlovci being dragged into a dispute over the hierarchic inclusion of Orthodox parishes in Austrian-occupied Bosnia.

[65] His formal resignation came in December, shortly after Ivačković made one final trip to Pest, and cited reasons of bad health.

[3][67] According to Păcățian, Education Minister Ágoston Trefort colluded with Anđelić and threatened to have Ivačković committed, finally ordering to get him to sign a blank resignation.

[68] They noted in particular that Ivačković had never mentioned his intentions before leaving for Pest, and were especially angered by his replacement with Anđelić, "regarded as the embodiment of pro-government clerical politics.