That's all working OK with the new versions of atril and mate-notification-daemon, thank you:
Repository : galaxy
Name : mate-notification-daemon
Version : 1.28.1-2.1
Repository : galaxy
Name : atril
Version : 1.28.1-3.1
although now I am having to do:
$ sudo pacman -Syu --ignore protobuf
because the new protobuf conflicts with libopenshot:
error: failed to prepare transaction (could not satisfy dependencies)
:: installing protobuf (30.2-1) breaks dependency 'libprotobuf.so=30.1.0-64' required by libopenshot