If anybody is having trouble with their saves made into a version prior to 0.7 not showing in 0.8, here's how I "fixed" it for me:
Let's say, I made a save in 0.6. When I load the game in 0.7, this save is showing into the "load" menu. However, when I open the game in 0.8, this save is not showing anymore.
So, to fix this, I have to load the 0.6 save in 0.7, then re-save it so that it shows in the "Load" menu of 0.8.
(I do not know if this is caused by the game version changes or by the fact I made those saves on another machine back then)
Hope this helps.