Can't move killed NPCs !

I have been playing almost 800 hours and this is first time I have a problem I cannot fix.
It all started when I downloaded bunch of addons and I noticed that when I kill a NPC I can’t move it’s ragdoll and also it doesn’t leave any blood marks when I try to shoot it. Also props go trough the ragdoll.
Well I removed some addons and the problem is not fixed, then I removed them all and still no fix. I deleted the local Gmod files. did not work. Then I deleted the whole Gmod folder and re-installed the game. still no fix. I also tried to search a fix on internet and I found one, but it is outdated and doesn’t work in Gmod 13. ( https://www.youtube.com/watch?v=JReJPOsXe7o&list=FL3BemPDev1j8KO8umGQ-3QQ&index=1 )
This glitch is ** VERY ** annoying. please somebody help me !

Try enabling “keep corpses” in the spawn menu on the bar on the top left

Thank you ! here, take a cookie ** gives a cookie ** you are the best