try windowed and record whole monitor and just crop it afterwards

EDIT: OBS eats shit when you render something other than OpenGL so check that in video settings bruh.

and run everything game,obs,steam as admin

Hello man I had same issue a long time ago but in CS 1.6. What worked for me was finding user.cfg (or userconfig.cfg something like that) in games folder, right click on it and change it to "Read Only". Though you should open the file and check if your personal binds are there and then save it just for safety. So basically:

1. Open HL1
2. Do your thing with the control settings
3. Close HL1
4. Go to HL game folder and find the config file
5. Check if it has your binds if not add them manually
6. Save and after that Right Click on the same file and fin checkbox for "Read Only"
7. Launch HL to see if that works
8. ....
9. Profit!!1!!1!!oneone