Sorry for the trouble. You're right, loading bounding boxes in old projects broke in 3.8. We've fixed in it v4 (the next version) now, but I'm not sure we'll do another 3.8 release. We'd not like to go beyond 3.8.99 and we are already at 3.8.97! The last two releases were for critical memory leaks.
A workaround should be to use the CLI to load the project with 3.8.11-beta and save a new project file, eg -i old.spine -o new.spine -r. However, embarrassingly this has a bug when trying to open old projects and it crashes with 3.8 and all versions back to 3.7.17-beta when we added those CLI parameters. Sorry! We've fixed that in v4 also. :wounded:
Please note that 3.0.00 changed how scale is applied, so you may need to fix up some of your animations manually:
Blog: Spine 3.0.00 released
