Broken Fillets

So I keep having this problem and please forgive me as I’m very new to Rhino.

I’ve split a cylinder and joined so I can have a cylindrical indent. Then fillet the edges on the flat plain so it is smooth. This gave me gaps at the other edges, so I fixed these but when I try to fillet it always breaks, as you can see in the final image. I’ve imported this model into F360 and tried the fillet there and it just works but I’m trying to move away from F360 ( I hate the cloud )

I’m obviously going about this the wrong way ? Please help. Cheers.

Hello - try MergeAllFaces on the object before filleting.
Any better?


That worked great.
Thank you, thank you Pascal.

Hello- the upshot is, some of the fillets need to attach themselves to surfaces that are not directly part of the selected edge.