Please file a bug and include a link to the YYZ of the project that doesn't work with Spine and the GMS2 UI.log file. You can create a YYZ file (a compressed file of your project) using the File > Export option, and the UI.log can be found in %programdata%/GameMakerStudio2 on Windows, but I'm not sure where it is on Mac (I think that it's ~/Library/Application Support/GameMakerStudio2 but I can't say for sure... should be easy to find though!). To file the bug report go to the Help menu in GMS and select "File A Bug" (supplied project files will NOT be made public and are only to help the YYG staff reproduce the error).