I'm not sure if this is a bug, a known limitation or a user error on my part, but this is reproducing in Xcode 11 and Xcode 12 betas.
I have package A, which is a dynamic framework, and package B, which is dependent on package A.
When building for simulator in Xcode, the app deceptively launches with debugger attached. However running the app produces the following error:
Dyld Error Message:
Library not loaded: @rpath/A.framework/A
Referenced from: /.../Example.app/Example
Reason: image not found
Looking at the produced app bundle, indeed there is a Frameworks/B.framework, but no Frameworks/B.framework/Frameworks/A.framework, causing the issue.