For a test back all of your clearance heights up to some large value, like 25" or so...regen and see if it still does it.. I see many times in multiaxis work that repositions hit the stock model

Hopefully he's not been wating 12 years for that answer

and that is exactly why I don't want the associativity.... My HMC programs are mostly production type setups....anywhere from 4-100 parts per tombstone, hundreds of OP's and transform heavy..... Last thing I want is a finicky Stock Model Op going dirty and causing constant regens on a file of that size...nevermind that it can't handle multiple models in multiple locations and that making a file any heavier with multiple stock models.....no thanks... Really depends on what the end user is doing

Here is the process I use to move stock from position to position....there may be other ways using other features... I define OP1 stock....run verify creating an accurate verification, I then save the out of verify as an stl... I import the stl onto its own level....I then copy to OP1 position solid to an adjacent level. turning off the OP1 solid and turning on the OP2 position solid..... I will select the stl and the copied OP1 solid, then using Dynamic Transform, flip, rotate and point to a position on the OP2 solid for accurate positioning... Once position properly, I "save as" the stl out to use as stock for OP2

Not knowing his overall plan....I put that out there... As I program several Intergex's, I typically, in my mind refer to them as live tooling lathes...though we do have a bout a dozen of those here as well..

I'd like to see which edge you used as a chain? When doing a 3D chamfer I always use the inner top chain....

If as your comments suggest you're doing this in a live tooling lathe.. Applying the KISS theory.... This part can easily be done with some simple turning, contours & drilling

You do understand that the tool path definition "Threadmill" denotes that it's for milling threads? Last time I checked, threads are full helical cuts wrapped around an axis... What you would want to do is create a helix that defines the amount of movement that you want to achieve and using contour >> 3D >> Then apply the arc3d chook... https://www.dropbox.com/s/eibssm6hwvlqlbk/PARTIAL ARC.mcam?dl=0 That will get you clean arc output ( N8 T8 PARTIAL THREADMILL SAMPLE CUT ) N8 N100 G20 N110 G0 G17 G40 G49 G80 G90 G94 G98 N120 G0 G28 G91 Z0. N130 ( 16 PITCH X .295 DIA THREAD MILL TOOL - 8 DIA. OFF. - 8 LEN. - 8 DIA. - .295 ) N140 ( PARTIAL THREADMILL SAMPLE CUT ) N150 T8 M6 N160 G0 G54 G90 X-.408 Y.0011 S2500 M3 N170 G43 H8 Z.25 N180 Z.2 N190 G1 Z-.2501 F10. N200 G41 D8 X-.358 Y.0008 F12. N210 G2 X0. Y.3582 Z-.2657 I.358 J-.0006 N220 X.358 Y.0002 Z-.2813 J-.358 N230 G1 G40 X.408 N240 Z-.05 F50. N250 G0 Z.25 N260 M5 N270 G0 G28 G91 Z0. N280 G0 G28 Y0. N290 M30 If that's how you've gotten there, you have already learned....I still learn new ways to use toolpaths to accomplish the needs of the design...when I learn something new, I consider it a good day.

In addressing chooks...chooks are small applications, that particularly early on were used to created functionality and see if it was used and necessary. Many early chooks actually migrated to full blown Mastercam functions and along the way, some little used functions or functions that have been made not necessary have been demoted to chooks...The coons chook is probably the most recent to be down graded...Netsurface has replace m uch of it's function...but it remains because there are those of us who still use it as in some cases it simply creates a better surface in some applications. The chook ability also provides a manner for people who want to develop their own hooks, for mostly their own use have an easy way in...there are other ways as well...chooks do have their place. I think you need to remember, there isn't anyone who knows this software in & out....there are more than a few of us on this forum that have been with the software since V3(abt 1990/1991) of those, many know much more about the software but we then/we/I will tell you there are still things to be learned... Over the years I have used other "high end" software and some of it I found to be incredibly powerful but so technical and difficult to use I have continued to this day to turn down ridiculous offers to program in that software.....they simply cannot pay me enough for the headache... I know you're fairly recent to the software believe me though, I have never, in all my years, been given a part that if it could be made, was not able to accomplish it within Mastercam.. Show up and cut it

Autocursor drop down

I find on our machines a 66.65/33.35 (2:1 approx) with a .0006" settings works best... You'll have to tweak to find what your machine like best

Could be depth settings, could be filtering settings..... If you're filtering the path try loosening it a bit....depth settings or check surfaces in that use shouldn't be needed

So send your file into QC it seems like you believe it's repeatable... Nothing anyone here says will sway you in any other direction

a COUPLE WAYS 2020 3D chamfer.mcam

Flowline..heck, even a 2D Swept will work perfectly fine SO many ways to attack it