Bug confirmed. This is a very strange bug in the PixInsight Core application, which for some weird reason this image has the 'ability' to trigger. I have been able to reproduce it with your image, but still don't have a clue about what could be causing it. I have not been able to reproduce this problem with any other image, either XISF or other format.
Fortunately, this bug is innocuous. To work around it, simply rename the image by double-clicking its view selector (or if you prefer, by selecting IMAGE > Identifier). Once renamed, the real-time preview will work without problems.
Thank you for detecting this, how to say, "exotic" problem
![smile :)](http://pixinsight.com/forum/Smileys/default/smile.gif)