On macOS High Sierra, using Safari 11.0, audio sources can now be controlled system wide from Safari. This is a problem because the Roblox chat audio is always on, so when I go to press pause/play on my keyboard, the new message sound plays instead of actually pausing my current playing music.
I think I remember this was happening prior to High Sierra but still support
This is still a problem and it’s very annoying.
I believe the repro steps you are providing are.
Step 1: Play music
Step 2: Go to Safari 11.0 on macOS High Sierra
Step 3: Try to pause and play music again
If those are the correct repro steps let me know and I’ll submit this bug report.
I can’t quite repro it 100% of the time. But you don’t need to be playing music before visiting the Roblox website. A simple workaround is to close the Roblox tab and it goes away.