Latest Studio, Latest IDEA (Ultimate) - this is a long-standing issue, I’m finally reporting it.
Often when editing message keys, the mode will switch between Advanced/Simple mode and display a placeholder value for a key that’s already been defined. I can’t exactly reproduce it, but I’m guessing anyone that uses this feature has experienced this and also hasn’t bothered to report it, as it’s not a huge deal, but it is indeed a bug.
The fix will end up in the next update then?