Data Sample is not showing in XML Viewer in Data mapper and template

The data mapper is not showing/reading data for added new sample input(XML). It has the same type of sample data already added previously which is showing fine. Those additionally added are not showing up. Can anyone advise what could be the reason please?

Could you attach a data mapping config (containing the 2 sample data files) that suffers from the issue?

I am afraid I can’t make that public. I will figure out how could I share something similar so that you can take a look. But I could say the problem is intermittent. I faced it before, but re-opening the data mapper and trying again (the same usual way) had resolved it that time. But the same is not working now with new sample files I am adding.