Not sure if it’s relevsnt but I had an old Oyster card st home with £12 on it. I cancell3d it and transferred the cash to my current OYSTERCARD which has an annual season ticket on it and cash for outer boundary journeys.
I nominated the station for transfer and on entering the outstanding cash and deposit was transferred but with an odd narrative.
When I got to my destination I checked the history on the old card and the cash was still there. I touched in and entered the station and asked a member of staff if the ticket was still valid. She told me it was. I said to them thst I thought it had been cancelled and transferred and she looked at my current ticket and said the narrative used wasn’t a transfer of product. The lady cancelled my entry on the machine and suggested I call the TFL helpdesk. When I did they said the card had been cancelled and there was no cash remaining. The cash showed as still visible 3 days later on the 4th day it disappeared.