Overlay turns red

Hi,

Ever since an unknown amount of updates(our photographers either did not notice it or never mentioned it as an issue) every overlay image has a transparent red color over it when we lower the opacity. In the example below I just loaded up a complete grey image. No red color there if the opacity is 100%. As soon as the opacity is set between 1 and 99% there is a red color visible. 

My first thought was that some kind of mask setting is on but turning everything off still does not fix the issue. Does anyone know a fix for this? 

It is not computer dependent because this issue is the same on 5 different macbook's. 

(Sorry for the Dutch interface language. It says Show mask never.)