Hello community.
I recently purchased a 1983 Citizen Cincom F12 lathe - Fanuc System 3T - with a Yaskawa Varispeed-616G3 VFD / inverter. The machine sat unused for a couple years and I have had some success bringing it back on line, however I am unable to reverse the spindle direction either while running a program that calls out a tapping cycle or by manual data input (MDI). While running a program and "M04 S400" is read in a G32 tapping canned cycle block, the machine goes into a "holding state" where the spindle continues to turn in a right hand direction, the cycle start lamp remains lit, and there is "no alarm" message. To get it out of it's "feed hold type of state" the program needs to be physically "reset" as pushing the cycle start button does not advance the program. As per commanding an M04 spindle reverse in MDI while the spindle is rotating in the right hand cutting direction, the spindle just comes to a stop as if M05 was commanded. With help I've received online and from the Yaskawa drive manufacturer it appears that the VFD is correctly connected with regard to FWD and REV terminals from the machine side to the drive, and also the relay between them is working. Out of desperation I thought I'd try reversing the poles of the main power coming in - using every combination of the three - only to find that other then the hydraulics not pumping in a few combos, I still "Could Not" get the spindle to go in the left hand direction. I've only hooked up a couple dozen 3 phase machines in the past but have never hooked one up where I couldn't reverse direction of rotation by switching a couple poles. Is this a condition created by the VFD that does not allow the phasing to be reversed? I'm a novice when it comes to things of this nature and would appreciate any and all suggestions.

Thank you all in advance.

[Attached photos show the digital keypad readout of the VFD in the commanded states of: M03 (F value, RUN and FWD lit); M04 (F value, STOP lit, REV not); M05 (no F value, STOP lit)]