Rent Payment Reversed NSF but tenant says funds were available

[NaTarrio Jones]

Hello BP. I currently self manage my properties using Buildium and I love it especially the resident portal and ability to accept ACH rent payments. Recently after over a year of succesful payments a tenant payment was reversed for insufficient funds, according to buildiums (R01) return code, but they are certain the funds were available. An NSF Fee was charged as well as additional daily late fees. There was a direct deposit on same day as the payment which would have made the balance enough to cover the rent payment. Her bank says that the deposit was there in time and there was no sign of a withdrawal attempt or rejected payment. Has anyone ever had this type of an issue and if so how did you resolve it? What proof If any can I request from the tenant to prove this? Thanks in advance.