There appear to be some problems with oaCapture on El Capitan. I’m still trying to run these to ground. I know this affects the ZWO cameras, but I haven’t tested any others yet. It looks as though Apple have fiddled with the USB layer a fair bit between Yosemite and El Capitan and code that works on all 64-bit systems from Snow Leopard to Yosemite is now broken 🙁
At the moment I’m afraid I don’t have an ETA for fixing this. Some workarounds for part of the problem have been added to libusb, but they don’t completely resolve the issues. I’m continuing to work on it.