After the first operation Turkey lacked the territory needed to establish a defensible partition.

refutedconfidence: low

A CIA judgement of 22 July, overtaken by the second operation of 14 August; State/INR had judged the opposite on the same day.

Supporting and corroborating evidence

The Turkish failure to render their corridor to the Nicosia enclave secure means that they lac[k the] easily defensible core area they would need to establish partition; they further lack sufficient territory to accommodate re[se]ttlement of the other Turkish enclaves...
DCI briefing text — LOC-HAK-471-4-5-9, CIA, 1974-07-22 · source ↗

Contradicting evidence

Double enosis is the more likely: it is a long-standing Turkish goal; once on Cyprus in force the mainland Turks are unlikely to withdraw and permit any other solution.
FRUS 1969-76 v30 D112, Department of State / INR, 1974-07-22 · source ↗

The Turks still have not given up the option of new operations on Cyprus, as hinted by Ecevit…
William Hyland (INR) — FRUS 1969-76 v30 D143, INR (Bureau of Intelligence and Research), 1974-08-21 · source ↗