How to reproduce: - Start PV, select demo (no acquisition needed), add the SPI decoder. - There should be a red "One or more required channels have not been specified" banner in the SPI decode trace, but there is none. - Add a new view, then move the right view slowly further to the left (to make the left one smaller). At some point the red banner will now appear in the left view.
Fixed in a998be27f155eee556f7ec521e5f70ce692026dc, thanks!