Cluster-scoped libraries aren't a one-time install — they get reinstalled automatically every time the cluster restarts. If that reinstall stalls (network path to the library source, private repo/artifactory unreachable, dependency conflict with the Hive connector), the driver's REPL never finishes initializing, so even print() or a trivial SQL cell just sits in "Running" forever, waiting behind the pending library install.

Move the Hive connector library to a cluster-scoped init script instead of the UI "Install Library" button. Init scripts run before the Python REPL comes up and are far more reliable/deterministic than the async library-install mechanism, especially for connector libraries with native/JAR dependencies.