TFC Mad Monday also does split categories. Check if their race time works for you.
https://teamtfc.com/mad-monday/
The Virtual L’Etape du Tour is also coming up (not a race, but should be race-like at the front)
Races that use the zwiftracing.app category system should also work for you. Most are team races, like Dirt Racing Series and the 5v5 Club Ladder. You would need to find a team that does these events at a race time you prefer, with room on a squad at your level.
https://www.dirtracingseries.com/
https://ladder.cycleracing.club/summary
You can also search ZwiftHacks for all races that have “all categories visible” and “same time starts” to find the mass-start races. There are many of them. See the Rules tab to see the buttons I pressed to generate these results.