It looks like we never updated the Panorama web server code to be able to handle the way that Skyline writes out the drift times in the .sky file.
"measured_dt" is what used to be written out in Skyline 3.7, but as of Skyline 4.1 and later, that gets written out as "ion_mobility".
Can you send us your .sky.zip file? I will make sure that we update the web server code to handle these documents.
In Skyline you can use the menu item:
File > Share
to create a .zip file containing your Skyline document and supporting files including extracted chromatograms.
If that .zip file is less than 50MB you can attach it to this support request. Otherwise you can upload it here: