There are two flip arguments for spr(), one for horizontal and one for vertical. You're only passing one to spr() in your _draw(), so the missing second flag (vertical) is defaulting to "no flip".

You basically need flipx and flipy fields in your player, set according to direction, and then to pass them both to spr().

I still can't seem to figure it out. :-/ What code would you recommend?

Here is the error:

spr (player.sprite, player.x, player.y,1,1,player.flip)

The SPR command has TWO arguments for flipping -- the first one for a horizontal flip, and the next for the vertical flip. You need something more like this:

spr (player.sprite, player.x, player.y, 1, 1,player.fliph, player.flipv)

That cart should have an "epileptic-inducing" warning!
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