looks like a high value in the CV setting makes it withdraw the tool early to try and keep a constant velocity

Not sure how CV interacts, if any, with the set feed rate of the thread cycle ....Art would need to comment...

displayed actual RPM in version  R3.043.022 being wrong above 600 RPM seems valid as it was fixed as soon as I installed Version R2.63

No comment on the old versions, they are history in my book, just let the old dogs quit hunting....... 
RICH