This begins with a company called Trust Codes that offers product tracing technology to A2 and Synlait. Apparently Penno was not forthcoming to A2 that he was a shareholder of Trust Codes through his investment vehicle Okoura Holdings. Signum the main owner of Trust Codes was in financial trouble and one of its creditors was Okoura, Penno's investment vehicle. Penno sought to put them in receivership, which really annoyed A2 because they had a good working relationship with Trust Codes management and had they known Trust Codes was in trouble they would have provided financial backing to them. Okoura had the power to put Signum and Trust Codes into receivership which would have affected A2's business.
A2's David Bortolussi had concerns regarding Penno's position as Chair of Synlait and Shareholder of Trust Codes who Penno had a shareholding in and his wife was Chair of Trust Codes too, meaning they ultimately has influence in both companies A2 was a big customer to. Bortolussi said it was unacceptable to A2 being a shareholder and customer of Synlait that Penno influence both companies and withheld his interest in Trust Codes. Ultimately they were very annoyed that he could have disrupted their business if he had put Trust Codes into recievership, along with apparently a nasty email sent to Bortolussi with negative remarks about Trust Codes CEO.
Could be a big reason why Penno resigned recent from the board. His past conflicts with A2 probably does not sit well with them.