T1 is connected, functions, but cannot be updated

Hello,

I've been using my descent Mk2i with the T1 transmitter for the past months with nothing but happy interactions.

I have just found the existence of a 2.6 update for the transmitter that I tried to apply before today's dives. I can connect to the transmitter from my watch, but the update fails after couple seconds. It does link with no issues underwater, and I'm confident I can type the last 2 digits of the transmitter ID.

Any advice?