Enemies knock the character down

Hello. I play a Titan warrior with a shield. Every few maps, I encounter a really annoying bug (is it a bug?): monsters' attacks start knocking me down as if they hit me while sprinting. I don't sprint. Monsters (any kind) knock me down with their first auto-attacks.
Reentering the location through a portal doesn't fix the problem.
Perhaps I just don't understand all the mechanics and that's normal. If so, sorry for bothering you. But when I'm knocked down, I don't have any debuffs, my armor isn't destroyed, and I'm not stunned. Being knocked down in this strange, random way causes me to die very quickly from attacks, which ruins the map and the overall enjoyment of the game.