While working in a topology I wanted to set an Exception. I tried clicking the box under the Exception heading expecting a pull down for True or False. I expected to see a pulldown as offered for creating rules. I tried selecting and unselecting the error, selecting and unselecting the feature, looked up help docs.
Finally it dawned on me to click the Preview - Details - Fix <- Ah Ha moment!
That is where I found the option to Mark as Exception.
Please consider allowing more direct interaction under the Exception heading so users can immediately toggle True/False/Clear
Full disclosure - ArcMap user for 20 years now transitioning to AGP.