I asked one editor just a few days ago about money. I just wanted him to confirm that they were still paying for contributions. A sister magazine of theirs went out of print recently, and this new editor has never mentioned money when asking me to produce work. This makes me nervous.
He didn't reply, but I did get a cheque for one piece in the post the next day, so they obviously are still paying. It's tricky though. Some literally won't talk about money. This editor literally won't even respond to enquiries about whether the work he's just asked me to do is a paid job!
I have others where relationships are easier. I may broach it in the new year. One of my US clients increased my rate without asking, which is fantastic. But most publishers have been cutting rates in recent years.
The other problem is that if they get a whiff that you're not happy with the rate, they'll just as easily get someone else to do the work.
When one editor offered me £50 for a job and I pushed back saying, they'd paid £80 last time, he just said he'd get someone else to do it. They've not published anything of mine since - including work they commissioned previously but never paid for.
It's very tricky.