No, it's not just your teammates who refuse to join the chat.
Overwatch's competitive mode is generally stressful enough, but a new bug that surfaced on September 26 has made the mode much more frustrating.
Around 7pm, reports started coming in from users on social media and official Blizzard forums that voice chat was being streamed in competitive (or ranked) mode. According to a Blizzard employee's response, the team is "reviewing" and will update as the night progresses.
The bug is causing it to appear as if no one on the competitive team has participated in the voice team chat, and only the current player remains in the voice channel. Regardless of whether their microphones actually work or not, each player also appears muted in their team chat menu.
Having only one player participating in the voice chat is quite common in some levels of competitive mode. However, most players noticed the error when trying to join the chat after multiple games in a row.
Based on reports from forum users and anecdotes from gamers, the spawning of the bug seems to focus on competitive mode. Other modes such as quick play and custom games seem fine for some users and not suitable for others.
Jambrix, representative of the tech support forum associated with Blizzard, updated the company's "call" at approximately 20:02 pm CT. This situation still continues.
Update 20:36pm CT September 26 : According to Jambrix, Overwatch engineers have “identified the issue” and will be working on a solution to get voice chat working once again.