In my case, the Braave was unfortunately made worse with the last update. A mini threshold between the bathroom and the hallway that it has taken effortlessly for over a year (without there even being any thresholds in the map) is now suddenly blocking it. I thought I could fix it by drawing a threshold in the map, but it didn't change anything. I am now waiting for the next update :-(

I don't have a direct answer to your question, but have you already tried to define the kitchen as a cleaning zone? The fact that it doesn't work with the defined threshold is quite strange...