Mac and HTML5 build exports are 'outdated'

It plays in the player on my Mac and I can make an export, which now stops playing right after start when uploaded to itch.io as a zip, which I've done just this way before.

Any advice maybe?

Only now, the game does not start the same way as it does on the player in my computer.

It shows the main menu but when I select 'New Game' the first scene loads but the start sequence is not played and no characters show up.

In the player on my computer, it runs just fine!

Could it be that things are in my browser cache that suggest a certain game state? (In other words, is it worth my time to find out how to empty the cache without emptying my whole browser history, because I'd love to keep that intact)

Or could there be an error in the way I autosave the game?

Does it work on your computer if you delete all bookmarks and saves?

I've now tried it in Chrome as well and there it runs fine.

Seems like it has something to do with browser caching, doesn't it?