No phono signal on DDJ-SX2

I just upgraded to Serato 3.3.1 and when I try to record the phono signal (i.e. from turntables connected to the SX2) into the Serato library, there is no signal. I have been digitizing my records into the Serato library for years using this method and it stopped cold yesterday. The Mac OS is the latest one - Sequoia 15, I believe.