Sorry about this: there was a mix-up regarding the "addon" function 
packages for gretl in the 2024d release (from a week ago). This 
affects our packages for Windows and macOS: these packages were 
built with addons labeled for "2024d-git", the previous development 
version, rather than "2024d" as should have been, with the result 
that they're not recognized as valid.
To check your gretl, go to "Help/Check for addons" in the main 
window. If the correct addons are not installed you should now be 
offered the option of downloading the correct ones, and hopefully 
that will put things right. (Just today I corrected the addons file 
for 2024d on sourceforge.)
Another way of correcting the addons is to install one of today's 
snapshots.
Windows: 
https://gretl.sourceforge.net/win32/
Mac: 
https://gretl.sourceforge.net/osx.html
Allin Cottrell