Arizona - Full time to part time; is that a separation of employment?

Good evening,

I have requested a switch from full time to part time status with my company. This was a verbal communication with my manager and agreed upon verbally, while being asked to submit an email stating I’d like to be part time officially and a date for which the status would change. Previously, I have utilized tuition reimbursement with a signed agreement that I would “maintain employment with the company for 24 months” after tuition payment. I was just advised that since I am switching from full time to part time, I am essentially resigning and being rehired in the part time status with the question of how I would be paying them back for that tuition. I am doing the same position, the same job duties, same work except in a part time role. The policy also states that repayment is not required for employees that are dismissed or resign in lieu of termination.

My questions to you after a lot of googling and being unable to find an answer, is this a separation of employment, in that I am not “maintaining employment”, so I would be on the hook for that tuition money? Is a change in work status really considered not maintaining employment? Is anyone able to point me towards some reading that I can help to defend my position, that I am in fact maintaining my employment with the company?

Thank you.