The issue here is that what is working in Capella 6.0.0 should not be working. This is a bug. Capella 7.0.1 fixed that bug…
Let me elaborate a little bit.
In Capella, there is an important distinction between data elements (Classes, Exchange Items, Data Types, etc.) and architecture elements (Logical Components, Functions, Capabilities, etc.).
When a project references a library:
Data elements can be directly reused by reference (for example in type definitions).
Architecture elements (such as Logical Components) are not meant to be directly copied or dropped into the project model structure from the library.
For architectural elements, the supported reuse mechanism is based on REC/RPL (Reusable Element / Replica):
You define reusable content as a REC in the library.
You instantiate it as an RPL in the consuming project.
In Capella 6.0.0, drag & drop of Logical Components from a library may have appeared to work, but this was not the recommended or fully supported reuse mechanism for structural elements. In more recent versions (including 7.0.1), the behavior is stricter and aligned with the intended reuse model.
If your need is to share common architectural building blocks across projects, REC/RPL is the correct mechanism to use in a library.