The roto tool doesn’t seem to work when you open a saved comp until you open the node and click on the roto bezier, this bug is apparent on OSX using 2.3.13 and 2.3.14
Same on Windows 10
I noticed that some heavy projects that hang Natron when opening, show the Roto interface without any reason just before the freeze. May be related. I’ll try to investigate further so we could make a precise bug report.