Can't connect to a specific friend

I play Bedrock on Windows 10, and occasionally Xbox One and PlayStation 5. On all three platforms, any time that I try to join my friend, who's on PS4, it says that it's connecting, but after 15-30 seconds, it says, "Unable to connect to world." With the Dirt Block background. This has been happening since early 2020. It's only that friend. She can join me, but i can't join her. I can, however, join other friends who are on various platforms, which is really strange. I contacted support and I was told to let you know this bug exists. On Windows 10, I've tried using Xbox Game Bar to join her, but it still says it's unable to connect.