Game stuck on first train scene with stormtroopers

This thread is old now, but hopefully I can help newcomers or those who continue to have this issue. For me, the solution was to keep holding L1 (LB on Xbox) until the trooper resumes attacking you. You have to keep blocking so the game can teach you that holding a block depletes your block force.

EDIT: this solution is actually for the next part of the same scene, inside the train car just after the blaster bolt deflection. The message is “Hold LB to block most attacks.”