Error connecting list-datatype of classes

I tried connect two nodes from the library and of the same type to each other. Even within a inactive if region, they produced the same error:ConversionError.log (53.8 KB)

Version 2020.1.7

If more info required, let me know. I’m not sure I can public share this project verbatim.

Basically the link between the nodes is semantically correct: type a inherits from type b and node a connects output of type a correctly to node b with input type b without a red link.
However, the error only went away once I used an explicit cast between them.