Why does the Uber Cortex no longer drop bases with triple synthesised?

A friend and I have made more than 100 uber cortex and they have not dropped triple synthesized bases, they have not even dropped with 1 Synthesised mod, was it a change made without announcing or was there a patch of notes that we missed?

The way we access Uber bosses has changed. Instead of activating a Keystone, it's now accessed through fragments from T17s. The 3-implicit Synth items were an extra thing added by the keystone (https://www.poewiki.net/wiki/Memento_Mori).

Should Uber Cortex still drop synth items? Definitely, in my opinion. Unfortunately that's not the case this league.