On my menu bar I have "Applications Places System". Yesterday I was working with an IDE.
Now when I go to Places I have my usual list of "Home Folder..Desktop.. Documents" etc.
If I press on most of these it launches my IDE instead of launching CAJA!
However If I press on these items on the Places list it launches the correct application - Computer, Network. Mate search tool, Recent Documents
Mate Desktop Environment 1.20.1
Ubuntu 18.04.4 LTS