Co-working or Coworking?

I'm proofreading a text for the magazine, and came across coworking. I prefer to spell it co-working with a hyphen -.

I've looked on Ngrams, wikipedia, and several dictionaries, and as usual with punctuation issues this one's all over the map. People in the office say everyone spells it without a hyphen and that I'm being too picky or old-fashioned.

What are justifications for using or not using a hyphen in coworking/co-working?

Please see this

"BiztipWritingTip response: Unfortunately, this question is still being debated. Both the CP (Canadian Press) and the AP (Associated Press) stylebooks recommend co-worker. So does the dictionary associated with the MicroSoft Word program."

But The Chicago Manual of Style and The Economist’s Style Guide (British) suggest that prefixes of one syllable, such as “co” can be used to form a single word. Therefore, coworker is acceptable."
http://ontariotraining.net/word-choice-coworker-or-co-worker/
I personally advocate "co-worker" as a writer.