Right clicking on a transaction will bring up the YNAB context menu
Right clicking on a transaction brings up the default chrome context menu
I cannot say exactly how to reproduce it from scratch, as it seems to work correctly at first, then after a while of prolonged use, it starts to occur - and a refresh seems to fix it.
The screenshot will show that toolkit is switched off, but it seems to happens regardless of whether the toolkit is on or off.
It seems to fix itself if I hit refresh.