Play Minecraft Ps4 and Nintendo switch together?

We have the following problem:

I play minecraft over the switch and my friend over the ps4.

We created a world together or he on the Ps4.

Sometimes he can invite me and sometimes we can't play together.

Why is that?

With me on the switch, he is not shown to me as a friend.

But if I look for him we're friends because it says "remove friend", so it is with him via the Ps4.

My Microsoft account also shows me that we're friends. With him too.

I hope someone can help us.

Because sometimes it doesn't work is really stupid

Should both of you be the Bedrock Edition (?). Without this, playing across consoles is not possible in this case. I played it myself for PS4 and sometimes with a friend who plays it on the PC and was a bit buggy with me too. So I would be interested to know where that is

Yes, we both have the Bedrock Edition.

It's really weird, sometimes it works and sometimes it doesn't.