Because if they would report it, then everyone might start to wonder about the veracity of the Hamas statements that they do believe.
The Jerusalem Post reports:
The Israeli Air Force (IAF) struck Hamas terrorists Samer Ismail Khadr Abu Daqqa, Ayman Mabhouh, and Osama Tabesh in a strike in Khan Yunis in the Gaza Strip, the military said on Tuesday.The terrorists were operating within a terrorist command and control center embedded in a designated humanitarian area of Khan Yunis, the IDF added.The military specified that Mabhouh was a senior Hamas terrorist, Abu Daqqa was the head of Hamas’s Aerial Unit in Gaza, and Tabesh served as chief of the Observation and Targets Department in the terror group's Military Intelligence Headquarters.
That is pretty specific. The IDF wouldn't claim to have killed named terrorists if they didn't.
Hamas responded to the IDF report by denying everything:
The Islamic Resistance Movement Hamas confirmed today, Tuesday, that the massacre of Mawasi Khan Yunis in the southern Gaza Strip is a crime that comes within the occupation's plan to exterminate the Palestinian people.Hamas stressed that the occupation's allegations of the presence of resistance fighters at the targeted site are blatant lies to justify these heinous crimes.She pointed out that the resistance has repeatedly denied the presence of any of its elements in civilian areas or their use for military purposes.
Hamas itself has published dozens of videos showing them shooting rockets and guns from civilian areas and humanitarian zones.
The claim is ludicrous - which is why the media doesn't even bother mentioning these denials.
If they did, then they would have to answer why they do believe Hamas when it fits their narrative.