Thank you @robert, I went through all steps and I found that there is a conflict with WP eMember Captcha (Version v1.1 | By Tips and Tricks HQ |). Whe...

Hey wpforo, this is a serious problem for me. Every time I make public_html/wp-content/plugins/wpforo/wpf-themes/classic/colors.css writeable, it is ...

I've over come this by replacing colors.css file on my server and disabling write access to stop the scripts from erasing it. Not ideal but the only s...

File permissions seem fine. Screen-Shot-2018-12-04-at-12.35.07-pm.png

I have since uninstalled and reinstalled both wpforo and wpforo advanced attachments and now I have a blank zero bytes colors.css file on the server. ...