I couldn't find any thing published for this so I had to create a field extraction for each individual query that we implemented. It took a few tries on each one. Just when I thought I had it, MS would through a new format in the query but they have been pretty stable lately. They are not the prettiest regexes but they are working for us.
Could you please help us, giving some idea about the extraction you used to solve this issue. I am also facing the same issue here, though we are able to fetch some data from MS Azure log analytics but data shows only header part.