I play on Jung Ma, and /say chat is not working in warzones. Until the last time I played, it was working, but now it isn't. Differences between now and then (to help isolate the issue) are:
1. I was F2P back then, am subscribed now (shouldn't make a difference, but still mentioning it anyway)
2. I was playing Regular Warzones then, and am playing Ranked now, still haven't played any Regs to see if the issue is there or not.
3. The last time it was working was before the hotifx patch I think.
Here's hoping for a quick fix.
Let me just alleviate your burden a bit
1. It's highly unlikely your switch from F2P to Sub is the cause, as there are other players and servers affected as well. It would be a _really_ strange bug if your change did it.
2. This is more likely, but again, as others have experienced it outside of WZs, not propable. If it is related to Warzones it most likely is linked to the start of season 2 (but again, I don't think it is, see 3 for the reason)
3. I noticed it first after Update 2.7.1 with that hotfix imho not improving any of it, but it's been reported on Monday before that update on Ebon Hawk.
And now to slightly crush your hopes
So far we haven't heard anything from the devs since that supposed fix on Thursday (which at the very least didn't fix it completely). This might be due to the weekend, but it's better to prepare for some wait, as hard as that is. *sigh*