repeatable, I still super early so not much in the game at all but any extrude will result in crash. running 5.5.4 to be specific right now and below is the error that it gives after selecting the face to use the extrude on.
Assertion failed: 0 [File:D:\build++UE5\Sync\Engine\Plugins\Editor\GeometryMode\Source\GeometryMode\Private\EditorGeometry.cpp] [Line: 400]