Looks like you have created a fault in the latest build so that you can no longer set date format in xml. This was working in previous release.
Try you example 16_rows_columns_manipulations\10_pro_format_xml.html
change format in grid_formatX.xml and it will put it out in the same format it reads it in as.
Date of Publication
Also your documentation says that %a is first 3 letters of day when in fact it only puts out 2.
i.e. Mo rather than Mon
“format” attribute of tag in XML or setDateFormat() method is needed to tell the grid how to recognize values comes from xml, no how to render them. If you have defined date format like “%d/%b/%Y” you should generate xml with the same date format.
If you have xml with cells values in the “%m-%d-%Y” format grid will render them without any transformation. But if you open last column editor and check any date you will see that changed cell has value in the “%d/%b/%Y” format. It means “format” attribute works.