Along with the recent firmware update to the Denon Prime 4 that lets it work in controller mode, Serato DJ also updated to 2.3.1 that comes with new additions and bug fixes.
Added Serato DJ Pro support for the Denon DJ PRIME 4
Added Serato DJ Pro support for the Denon DJ SC5000M Prime
Fixed a bug where the Audio Setup panel did not open on first connection of some DVS mixers
Fixed a bug where playback triggers twice when pressing Stutter Play once, on the Reloop ELITE
Fixed a possible crash when selecting the FX Pad Mode on some primary devices with an OSA connected
Fixed a bug where Active Loop turns off after MIDI mapping Akai AMX touch controls then turning touch mode off
Serato DJ Pro 3.2.1 Release Notes https://serato.com/dj/pro/downloads/2.3.1/releasenotes