So, I own CDJ 2000 Platinums, and have no issue connecting via HID mode. At my residency, they have CDJ 900 NXS and DJM900 SRT. The problem I have is very sporadic in nature. This is all connected by a powered USB hub and an ethernet switch. The one USB for the hub goes to MacBook Pro ( 2012 model ) on Catalina, 10.15.3, 16GB of RAM, with Serato DJ Pro ( now on latest version ). Some times, plug in, and all devices link to PC as they should. Some times, the mixer does, but decks won't. They usually will say, Connected to PC, and get stuck on that screen, and never let you choose deck and link HID Mode.
I've found, sometimes unplugging USB cable, and powering down deck would sometimes get it to work, other times not. Sometimes one deck would work and other wouldn't... sometimes it'd take an hour, other times, 3 minutes.
I've even gone in and changed MIDI channel and sometimes that worked, sometimes not.
IS there anything definitive to check to remedy this??
Sometimes, even though decks linked, they would be flipped despite deck numbers being correct ( 1 & 2 ), but on Serato, 2 would be on left, and 1 would be on right...
It's a great concept, but HID mode has been the only thing inconsistent about digital dj'ing.