From time to time gretl gets stuck by saying that a variable is in use by a model when its not. See the attached example. Only one model is build and saved but when I try deleting the variables not used in the model its says that it cannot delete them because they are in use. (clearly they are not) (you cannot delete NRCPI_low in the example file). I remember this used to be a old bug with ARMA model but now it shows with other models (linear models with ar error term).
Gretl version 1.9.1