If you want problem-free filleting. you need to make sure your surfaces have good tangent continuity.
In the enclosed file I fixed the one surface that was not tangent (shown in red) with MatchSrf. You can then get a continuous fillet loop that can be used to trim and join to the base surfaces. ring6x.3dm (164.7 KB)
@lopacki Danny if you can accept that there is no need for jewellers to be Class A modellers then perhaps try Sub-d with Rhino. It makes the fillet problem go away and I find it much quicker.
I hear it may also help stop the demand for Emu feathers and save a lot of our Emus here from butt pain Photos of a quick play in T-Splines attached. Good luck.