No, it wasn't just you: Slack was down for an hour
Update: As of 11:54 AM Eastern Time/17:54 Central European Summer Time, Slack has reported both via its status page and social media that "all functionality is now restored." No reason or further details about the outage were given.
If you found yourself waiting for a reply in your workplace's Slack workspace, don't worry, you're not being ignored! Slack is just down as of 11:00 AM Eastern Time/17:00 Central European Summer Time.
Slack confirmed the outage via a notice its official system status hub. Summarized as "Issues with messages sending and slow performance," the full notice does not elaborate much further beyond their development team being "on the case" and the issue being "actively [looked] into."
If you find yourself wanting for something to do while waiting on a reply from someone in Slack, why not look into some alternatives? Self-hosted options such as Mattermost could be good if you have the infrastructure to support it, while commercial alternatives such as Microsoft Teams benefit from the global data center infrastructure that Microsoft operates if you find yourself needing a team communication app with that kind of scale. Of course, there are plenty of options in between those two extremes as well that could fit your use case if you're feeling adventurous (or simply curious) about Slack alternatives due to recent downtime.