What GPU do you have?

Also, screenshot?

Screenshot #1: http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=808504648

My GPU shouldn't have anything to do with this. This problem occured a few days ago. The same thing happens with the portal gun.

Screenshot #2: http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=808504703

Yeah but your gpu may not support rendering portals

I use an integrated graphics card in my motherboard, but why would it just stop rendering the portals all of a sudden?

Did it work previously then? On the same PC

Yes, but it just stopped working a few days ago.

Same problem, nvidia GTX1080 it worked the first few times on my computer, but started doing this about a month ago

It did happen just after a addon update

Same thing happening here with APU graphics

Can you guys try disabling all addons except doors/rewrite and see what happens?

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=554915029&searchtext=gpowers

Thanks Dr. Matt, this addon was causing the problem with the doors. Once I removed it, the issue was gone.

Interesting, not sure why that could cause a conflict. Can anyone else confirm that addon is causing this issue?

I can confirm that Gpowers was causing the white portals, once removed I could see the interior from the outside whilst the doors are open. All I can recommend is disabiling gpowers,

the same thing is happing to me but it is black