On the Block User popup, the list of previous blocks (sometimes?) reports incorrect block durations. It recently reported "indefinite" and "will not expire" for all prior blocks of user 126.96.36.199. I have seen and recognized this a number of times, and have probably also seen it without having recognizing it.
Version: 3.1.12 build: 2563 3.1.12-1-ga0be145 without python support, compiled using QT 5.4.0 Running on QT 5.4.0