The logging for OpenCL is actually bugged. It says "enabled" when it's actually disabled, and it says "disabled" when it's actually enabled. @Xaymar is aware of that and has fixed it for the next release. So when you say the log showed it enabled, it was actually disabled.Not ideal though really.
I noticed in the logs from earlier that opencl is enabled by default in some of them and recording seemed to work? Seems to cause problems when I manually fiddle with it.
In fact I put the preset back to 'default', and recording worked. Looked in the log and opencl is enabled.
I'd go with what @Xaymar recommends here and leave it disabled for now. He and I both think this sounds like a bad driver installation, or some other system-related oddity.