Hi guys -
Can't find any reference to this problem around here, but apologies if it's covered somewhere else. After saving and quitting Simon, when I restarted the game later on, my savegame list contained no save files. I have it installed at G:Program Files which I figured might be the problem...?
Anyway, I verified that the savegame ('simon1.001') was present in that folder (phew!). I solved the problem as follows:
- start SCUMMVM up in isolation (in your install directory, scummvm/scummvm.exe)
- if it's not there - it wasn't in mine - add Simon to its list of games. Select 'Add Game' browse to your install directory (GoG.com/Simon the Sorcerer) and hit 'Choose'
- set the save game path (options->paths->save path) to be the install directory for Simon.
Now when I run the game, my save file is present in the list and valid. I've used ScummVM a fair bit in the past, so thankfully I had an idea of how to fix it - hopefully this might help someone else out in the future. Or ideally get added to the docs somewhere prominent if it isn't already.
edit: NB - just checked and in fact the savegame ONLY appears when launching the game from inside ScummVM. If I launch it from the shortcut, the game isn't there. So you guys might want to look at that...

The installer uses a custom config file (simon.ini) for ScummVM, which will need to be edited directly. Open 'simon.ini' in text editor, find the '[simon1]' section, and check the 'savepath' setting is set to the correct directory.

Yeah there was no savepath entry in there; adding it fixed the problem when running from the ini file. Slightly strange that it manages to save the file in that directory, but then can't find it to load again :s