Thank you, this is something I had tried, but it didn't work.
https://imgur.com/a/sZjxZnS I probably did something else incorrectly.
I figured out a way with random clicking - there is a tiny button on the group chat called Enable/Disable message filter, and this worked. Maybe both things need to be done together because the Events and filters check marks alone don't seem to be effective.
While I am here though, I had a crash, and I'll post the crash log here.