I am using the #@ script parameters, I noticed that the persistence set up an unexpected value (actually 0) when the value entered by the user is the one defined as default.
#@ int (label="delta", min=-5, value=10) delta print delta
The persisted value is indeed recovered in every case, except if the user enters 10, then the next time the script is launched the value is 0 !
Tested on 2 different fiji installations, with Jython and the IJ macro language.
EDIT : Gihtub issue
EDIT2 : It works fine with