Why can't I call up the members of my email groups when using Firefox, but can when using MS Edge?

I have three email groups on Comcast.net. To view the members of these groups when using Foxfire, I have to put them into the addressee box. However, if I use MS Edge, I have no trouble viewing them by opening the group using the usual prompt. This has been going on for a long time. I am running Windows 11, but don't know the version of Firefox, just that it has been updated several times since the problem began.