If you crouch near an enemy (player/monster/dummy) while in invisibility, the invisibility is dropped and you are detected. Even if this happens at a not very close distance to the enemy and from behind. At the same time, crouching in invisibility far from the enemy does not reset invisibility and you can then safely exit invisibility and be hidden. Also, if you get up from crouching in invisibility near the enemy, everything happens normally and you do not leave invisibility
I think it makes the experience of being a hidden character very bad. If you are playing as Nightblade and want to crouch to hide without using resources for Shadow Cloak, there is a chance that you will lose invisibility and not be able to hide.
Video:
https://youtu.be/We8m13KJQp0