I never had problems using this interface on my macbook pro and logic pro x. lately i downloaded the OSX EL capitan version 10.11.3 for my mac.
I turn on my presonus audiobox 1818vsl then went into logic pro x to get it connected for recordings, a box will come up on my screen letting me know my interface is connected with logic pro x and if i want to use it with the program, i say yes, then 2 seconds later a side box comes up saying "audio device has been removed". Long story short, logic pro x knows the interface is connected but then disconnects it or refuses to use it.
So instead i went into my mac's system preferences - sound preferences and then into the input channel box, and as i am looking at the input available, the audiobox input appears under the built in microphone input for like 1 second then dissapears for 4 seconds and repeats. as if the mac its self doesn't want anything to do with the interface and refuses to connect it. if someone has any idea please help cause i can not record anything.