Islands which had been occupied by Greece during the First Balkan War and adjudicated to it by the Great Powers precisely in exchange for its abandoning claims on Northern Epirus/southern Albania. From the Greek POV, leaving some claimed lands to a weak and unstable state like Albania is one thing, leaving strategically important islands in Ottoman hands, with no sureties about their population's fate, is quite another. They chose the islands in early 1914, and they won't change that later in the year, especially since Venizelos saw the opportunity (as happened IOTL) to reoccupy Northern Epirus all the same.
Given that by July 1914 not only is the Greco-Ottoman naval race in full swing, but the Ottomans are actually beginning ethnic cleansing of Greek populations from the coasts of Anatolia, getting the Greeks to agree won't be easy. Plus agreeing to an expansion of Bulgaria that would cut Greece off from its ally Serbia would be seen as a suicidal move, only preparing the way for a future Bulgarian invasion of Greek Macedonia. The deal would have to be reworked into a far more comprehensive agreement among all sides (who were not consulted IOTL), and strong British backing of it, before Venizelos committed himself to it. The agreement was more wishful thinking on the part of Enver (regaining the Aegean islands, the hot topic of the day, would raise his prestige, and if he could manage to keep the Ottomans out of the war, all the better) rather than a well-thought-out political arrangement.
