[Answered ]-Python regular expression not matching file contents with re.match and re.MULTILINE flag

According to documentation, re.match never allows searching at the beginning of a line:

Note that even in MULTILINE mode, re.match() will only match at the beginning of the string and not at the beginning of each line.

You need to use a re.search:

regexString = r"^\s*"+item.feature_key+":"
pq = re.compile(regexString, re.M)
if pq.search(data):

A small note on the raw string (r"^\s+"): in this case, it is equivalent to "\s+" because there is no \s escape sequence (like \r or \n), thus, Python treats it as a raw string literal. Still, it is safer to always declare regex patterns with raw string literals in Python (and with corresponding notations in other languages, too).