Steps to recreate;
-Play game until you get to the point shown on the screenshots. (on lowland meadows right after you talk to Lara and take the elevator up, get to the staircase right ahead, there is a pit near it)
-Move into the pit right near the staircase and try to move under the staircase
-You might get stuck, start playing the fall animation, and be unable to move
Exitting to desktop and coming back solved the issue, I’m guessing because you are so close under the ground, your character just spawns above ground when reloading.