As of High Sierra 10.13.4 a large number of bindings we depend on in CL game community are broken due to a macOS bug that only manifests in SBCL.
This has been reported on the #sbcl IRC channel but the developer we spoke to there informed us that he would not be looking into it and that the only option we have right now is to opt into the mac beta program and test the next release.
As that is unpractical for many we strongly suggest you use CCL for the gamejam if you plan on working or shipping your game on macOS.
We are very sorry about this and, whilst we will keep digging to see what workaround we can find, it is certainly not going to be found before the end of the jam (as most of us are participating too :] ).
If you've got any skills in this area and want to help out you can find the issues tracking this below:
Alright, back to the jamming!