I downloaded and installed SH 1.5 without incident, but the only games I can load are those autosaved by SH 1.4. When I load any game I saved in SH 1.4, I get a "Load Game Failed" message.
I tried and successfully loaded one of the autosaved files, then tried to load one of my games but got the same result.
Additionally, under SH 1.4 I never had an issue naming, saving or loading games, whether on the surface nor submerged.