When you posses Demon Spawn(or maybe thief) and get level 11(10+) you become a dragon and still possesing it but all elements disappears from creature panel.
Also i had next question: when creature type changes is not there a point to save his name?
This was in the original DK as well.
Maybe it's a transitional issue, where it can't replace a panel with a new panel whilst in possess mode. I reckon it's the way the panel information is stored and recalled, similarly if you query a creature whose primary attack is their 7,8,9,10 attack, you will not be able to scroll to see their 1,2,3,4 attacks, it will scroll from page 5,6,7,8,9,10 to a blank page to the info page.
But when you die as vampire and get teleported to the lair(and lose 1 lvl) as instance panel is being handled properly
Yeah but that panel doesn't change, as it doesn't show the level in the panel. The changing creature is a whole new panel. But everything with the vampire just refreshes the health.
The vampire even gets to keep his high level spells.