Just when you think your'e getting places, Fusion kicks you in the whatnots

Here is a share link to the part i was hoping to add the fillets to, several hours later not only did i not get the fillets added, I cant even figure a strategy that works how i want it to ;(

A360

What i was hoping to do was machine the part from each side towards the centre-line from a larger lump of stock. I wanted to leave a frame of stock around it so i could flip it over and machine the back - it would be machined in a pocket basically. I can select the mid-line as a depth easily, but no matter what method i seem to choose, the paths either do not cover the whole perimeter or they cover the whole stock surface which means no pocket and side 2 would be seriously harder and likely need a fixture etc.

When doing the back, i wanted to leave holding tabs so it didn't fall free.

Not sure if that makes sense but i know what i want just not how to get it