It seems like you are not only migrating from SC to Emotion, you are also upgrading emotion packages in the process.
It is now no longer possible to use the latest version of @atlaskit/button (15.1.7, published 19 days ago) in combination with the latest release of @atlaskit/select (15.0.0, published 6 days ago). Installing both in the same project will result in the following error:
The reason is that @atlaskit/button transiently installs version 10.0.29 of @emotion/cache, whereas @atlaskit/select installs version 11.4.0. There is a breaking change between these two versions.
Would it be possible to ensuring that we can use multiple AtlasKit components in our projects becomes part of the acceptance criteria / DoD for Log in with Atlassian account