[CM12] Nexus 5 is not detected via USB when plugged topic

I have a strange issue, when i connect my phone over USB the computer does not recognize my phone, there are no options in the notifications, when i enable usb debugging the phone just reboots. When I enter TWRP and enable MTP there everything works fine. I have CM12 installed since the first nightly and dont know currently when the problem occured but I always flash the latest nightly available. I would like to prevent a factory reset to fix things.