SLC HSTP step/dir servo needed

[kaiser_will 65]

In process of migrating our legacy SLC-5/04 based machine which has 1746-HSTP1 stepper/counter modules controlling stepper motors. Got design with stepper motor that exceeded max avail motor size so had to change 2 axes to servo. At start of design, have a full cabinet built up just needed 2 more HSTP1 modules and servo controllers. Pitched challenged to Rockwell and sales engineer suggested the new Kinetix 3 servo controller. Went that direction to find out it has not been done before and thusly A-B has no application tech notes for such. In end, it works (kinda). There are 2 random situations in which the K3 servo controller with either not respond to pulse train and direction commands (from HSTP1) or will continue to move and not stop. Looking for proven application of stand alone servo controller controlled by 1746-HSTP1 stepper/counter module in a SLC rack. Have come across stories of Yaskawa and Mitsubishi. Looking for more detail.