Yeah I also cannot recommend that people who use subtances a lot to upgrade their existing projects to 2018 yet as it seems there is no working upgrade path? All the material links were lost as the plugin seems to only create new materials and pre 2018 materials are destroyed. Also almost all subtance generation settings were also set to defaults. Importing the plugin to project before or after opening in 2018 did not seem to help. Importing the plugin afterwards leaves the console spams that plugin should be installed from the store even though it was just a moment ago. Reopening the project does not help. Only right clicking the .sbsar file and using re-import fixes the errors but results in the above missing links and value wipes.