Hand Value at 0 is null

[maru-chan!]

Was testing out a deck and after searching tengu off declaring fire formation tenki, the hand shuffle animation played, but got stuck halfway through, at the point where all the cards are behind one card. I tried manually shuffling the hand, but nothing happened. The chat displayed something along the lines of "hand value at 0 is null" in the black bold text used for stuff like declaring effects. Attached is recording. Relevant part is after siding.

https://www.duelingbook.com/replay?id=312780-25314058

[DarkPhenix]

That means the server side thinks that card is not there, yet you are attempting to select the card, so it is returning a null value