Parallax has changed throughout entire website

Greetings Xtemos team!
Over the years we have made extensive use of the background parallax feature.
At some point, and we’re not sure when, something has happened and now all parallax rows show a white background until the image comes into frame. Playing around with the “Background position” setting does not make any difference.

I have included an example link as well as a screen recording.

Thanks in advance for your help.
Tom