The weirdest random bug I've encountered so far and can't figure out the source of...

[sanicstudios]

Simply put:

Made a map in UDMF, copied it into a D2 format to make a fully vanilla version of it, now all things on the map are sliding to the left, including the player.

 

I have no idea what caused it and I'm genuinely confused.

[baja blast rd.]

Can't be sure without seeing the map, but my guess is an action # used by a zero-tagged linedef for a single local event like a floor or ceiling moving in your UDMF map, is the same action # used by a scrolling floor effect in Boom.

 

If zero-tagged, that unintended scroller would affect most of your map. And if you're playing the map in GZDoom, it doesn't automatically "turn off" Boom actions if those exist in the map. 

 

Whatever the exact cause, there is probably some unintended action somewhere. You can look through the Tag Explorer to find it more easily. 

[sanicstudios]

Appears that was it. I usually immediately clear all linedefs and sectors on converting but obviously forgot to this time.

Thanks.