1/ On January 25 at 8:28 UTC, @kusamanetwork runtime RT1001000 triggered a chain reaction affecting all parachains, including Moonriver (Moonriver block before stall: 6012045).
See blog for details &, if you run a node, to verify your node isn't affected.
2/ The issue, related to Kusama's code changes for Asynchronous Backing activation, caused a stall lasting approximately one Kusama epoch (1 hour).