My last problem is that the character will run into a "wall" which is declared as a solid, yet the character will magically "jump" to the top of the wall or even stick to the sides half way up/down the wall... even if I change the collision mode for the player to bounding box (which I don't really want anyway). I fixed that by making an event "if player collides with wall">"player stop" but this creates undesired results depending on the current animation frame of the player if they are running.
This happens when your animation frames aren't a consistent size (which is almost always when it comes to animation). What's happening is that on one frame your animation might be 20px wide, then your character hits a wall. The next frame is then a pixel or few wider, which means your character is now intersecting the wall.
The platform behavior automatically pushes sprites up when they're stuck like this. This is necessary for gravity to work... when a sprite is falling, the platform engine checks for intersection, and if there is, it runs a quick loop to jump the player to the top of whatever it's intersecting.
The way to work around it is to make a separate sprite for the player that is a constant size. A one-frame, one direction, single-animation, perfectly rectangular bounding box. The bounding box is what you apply the platform behavior to. Then you make it invisible and overlay your animation frames on top of it.
It's best to make your bounding box a sort of "average" size for your sprite, something that covers the main torso/head and goes straight down to the floor from there, so that extremities don't get in the way. If you need pixel-perfect collision for enemies or bullets or whatever, you could always use the player sprite to check for that (though I wouldn't recommend it for Mario type games).
Anyway, with a Flashback type engine you might want to avoid using the Platform behavior altogether. I know it would be a lot of work (one reason why mine is on hold) but it's such a unique type of platforming that trying to recreate it with the Platform behavior is probably a lost cause. Things like running and jumping aren't so much about moving the player sprite in x/y over time as it is about playing a specific number of animation frames to get from point a to point b. In Flashback all movement is very pixel-precise... the player's feet always land in the same place, he always jumps the same height/distance, and he's always lined up exactly with platforms when you stop, etc. The Platform behavior in contrast is very loose and sloppy in that regard. Trying to whip it into shape would be a lot of work, and you'll likely go completely insane from it.
As for the animations stopping, go ahead and post your .cap or PM me and I'll take a look at it.
Sorry for the WALL OF TEXT but hey, that's my style