Renato,
Please disregard what I said and go with michael's advice.

Michael,
Seems more of an anomoly thing than a bug. and yes it has to do more with the fillet, then boolean, then fillet again. For instance here are three files. with the "boolean lines for MG_2.3dm" I generated the other 2. I also generated the same operation with 5 other attempts that worked fine.

One file lost a surface during the action. the other is the failure to fillet thing. After the failure I may have joined the 6 edges and deleted them then tried again.

Anyway, after doing it for 10 minutes, then paying closer attention to selecting things in some kind of fashion, it seems to do it ok. And if I do like you suggested and wait to do them all at the same time it seems to function correctly.

My previuous statements about the "Boolean" leaving lines does not seem to be accurate.

Thanks for the attention.
Burr