puzzle with multiple solutions that aren't reconized

lishogi.org/training/IgzMU
I know the puzzle system is new and its wonderful but I'm sure there is a real problem with this puzzle the solution was straight forward but it bugged me that there were two solutions so I checked with the engine and it agrees that after Rx61 it doesn't matter if you promote the rook either way its checkmate and in the same amount of moves now there may be an arcane rule that the engine doesn't abide by that forces the promotion and if so please let me know but if not this puzzle is broken because it says without promotes is a failure.

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Yup there are a bunch of lines to a mate in 3 in that puzzle.

I've encountered this puzzle quite some time ago and yeah, for some reason it doesn't accept that move even though it is a valid mate, no weird shogi rules of the sort. I guess just as a rule of thumb, promote every piece that you move even if there is an unpromoted variation that leads to the same outcome. xD

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