Created attachment 193819 [details] calc sheet Voorwaardelijke opmaak Voorwaardelijke opmaak reageert wisselend bij het invullen van een optelling in een andere cel. zie bijlage.
Quick translation: "Conditional formatting reacts differently when entering an addition in another cell. see attachment".
I think you have not used properly relative/absolute references in MAX(B1:B10)->MAX($B$1:$B$10) E.g. for B2, the max value with relative reference is calculated MAX(B2:B11) But please explain better with what value do you want to get with the conditional format. This site is used in English, you have good translators for that, like https://www.deepl.com/translator if you don't like Google translator.