for the last few updates none of my saved files have been working I've used multiple web browsers and even downloaded the last two previous updates off of itch and just hasn't been working.
I don't know anything about the web versions, you would have to ask whoever made them. If you start a new game on the itch version, your save will work on the next update.
Changing versions almost always breaks saves. You can't play web then offline, or modded then not modded. That's just how Renpy works