It won't evolve. What most Tamers fail to do is obtain a High Win Ratio at the Child stage. Many make the mistake of battling less often at the Child stage and wait for evolution to the Adult stage. Be mindful, in this case a Greymon with 30+ battles may not be enough for an evolution to a Metal Greymon. In my case, in a Pendulum Version Zero - Virus Busters, both my Agumon and Greymon had a Win Ratio of 100%. Additionally, no Care Mistakes. This may not be possible in every case but if your Child stage Digimon, in the case of a Pendulum Version 5.5 Metal Empire, a Toy Agumon or a Hagurumon, it is important to have as high a Win Ratio as possible before evolution to the Adult stage. If sucessful, a Greymon if properly cared for, having 30+ battles and a high Win Ratio, a greater probability exists of evolution to the Perfect or Complete stage. My Greymon was around 6 when it evolved to a Metal Greymon. Eventually, my Metal Greymon with no Calls, Win Ratio 100%, evolved to a War Greymon.
I can't emphasize this enough, don't wait until your Child evolves to begin obtaining a high Win Ratio prior in attempting to reach Perfect, the longer you wait to train properly and battle, the less likely it will evolve after the Adult stage. This is most likely what has happened in this case, I have seen this on many occasions over the years.
