Yesterday there was an island in the mines from which I jumped to grab "?" quoins. While I was in the air the screen graphic switched momentarily to the preliminary location-loading graphic for that section of the world (the graphic that appears right after you click on a signpost).
The wrong graphic intruded each time I jumped and was in the air (several times). The jumping&grabbing actions all worked. There was just this fleeting appearance of the wrong graphic.
Sorry I can't remember the exact location. I will try to retrace the steps next time.
Now that I think some more, the misbehaving island may not have been in the mines but in one of the offshoots somewhere in the direction of the Hole to Ix. Where is where on that part of the map is still confusing to my brain.