[Marttt]

you can try removing my plugin and check if the bug stops

[L4D1 & L4D2] Miss Shot/Shove On Tongue Grab

Don't know if this could bug like you said, but is one of the plugins that prevent SI from getting damage (only from the grabbed attacker btw).
In the worst case the SI would be invincible only from one client and not from everybody else

Probably would glitch the shove function aswell if is that plugin.