It seems that since the last update, some users have been having an issue with an error message (which doesn't stop the program, but may be making a bad forecast) saying the GFS (or other) data is more than 24 hours old. I have not figured out yet what it might be about the last update that would cause this to start happening now, but I do have what might be a fix. Please try this new version (but save your current wxsim.exe file somewhere in case there's a problem with this update):www.wxsim.com/wxsim.exe
Just use that to replace the wxsim.exe you have.
This one not only updates the date, but also the time, BEFORE trying to import data. I think it will provide a layer of protection against that error (which I'm still trying to fully understand).
Meanwhile, I have found issues people should be aware of, like making sure your DST boxes are all checked (if that applies). Also, I found one case where a customer's WD log files appear not to have updated for over an hour during the night (so he got old data becase of that). Just things to be aware of.
By the way, I would be interested to hear from people who have Version 12.10 and have NOT had any error messages with the first run of the day. I'm trying to figure if it's a time zone-related thing, or something about the choice of run times (and anything I might have changed going to 12.10).
Please let me know if this fixes things!