When running my test suite under Cloverage, I get a bunch of "No implementation of method" exceptions for protocol implementations of records.
The implementations are defined by (defrecord MyRecord [..] MyProtocol ...) but if I change them to (defrecord MyRecord [..]) (extend-type MyRecord MyProtocol ...), they start to work.
A coworker pointed out that defrecord creates the interface implementations for the protocol while extend-type creates the protocol implementations, so that's probably why it helps.