"Instant" glue allows you to turn the blanks soon after gluing.
What you CAN do and what you SHOULD do are usually NOT the same.
I did thousands of pens using thick CA and never "roughed up" brass. If the brass felt slippery, I did dump it into Acetone to clean. I also spent 20-30 seconds putting the tube INTO the blank, rotating it, pushing in and out, in short making certain the glue was spread thoroughly, from both ends of the blank.
Then, unless it was a class that had to have the pen that day, the blank sat at least 24 hours to cure. I had fewer than 1% that ever slipped after initiating this practice.
Also realize the "shear strength" of CA or epoxy is NOT great. But, what would make it break loose from the blank?? A SHARP tool, presented properly, will cut the material and should create very little stress on the glue joint. I have come to believe that using a pen mill is a bad idea for many reasons, including the ability for the mill shaft to adhere to the INSIDE of the tube and make it spin, if used before the glue inside the tube has cured completely.
So, if that joint is breaking, it may be your "cutting" technique or the amount of time you allowed it to cure, or the amount you "spread" the glue.
Millions of pens have been made by hand pen makers using CA, epoxy, gorilla glue and others. There is a group of penmakers who claim each of these is the "perfect" adhesive.
Personally, I believe any of them can be "perfect". IF they are applied correctly and allowed to cure and then turned with reasonable technique.
Hope you find your real problem, soon!! It is unlikely that it is the glue.
Ed