Nixon, who had worked at the press supplier for eight years, left his post last week and did not attend Drupa.
The company statement announcing his departure said he was leaving due to "conflicting interpretation of strategic vision".
KBA UK managing director Christian Knapp told PrintWeek: "The structure of the KBA UK board has changed, and there was a difference in opinions about the future. It was a mutual decision that Mark would leave."
KBA’s worldwide sales director for sheetfed presses, Ralf Sammeck, and group chief financial officer Axel Kaufmann also sit on the UK board of directors.
Knapp praised Nixon for his contribution to the company and "undoubted commitment and focus" and said he wished him all the best for the future.
He said Nixon’s departure was not connected to the yet-to-be confirmed loss of major customer Buxton Press, which is understood to have selected Heidelberg for the press element of its £11m re-equipping plan.
Knapp will take over Nixon’s responsibilities for an interim period, but it’s understood KBA intends to recruit a replacement for Nixon.
PrintWeek was unable to reach Nixon for comment at the time of writing.