Synchronize not working?

[Oukumotou]

Although this seems stupid, I still want to ask. When I used the ability to catch Pokémon, the chance of getting the same Nature was quite good, but it seems that it will no longer work on a certain day this month, and it has continued to do so. It may be working, but I am sure the probability of it is not 50%. A few days ago, Smeargle did not have the same personality until the 24th Smeargle. This kind of problem has appeared in all Pokémon. Recently, I caught hundreds of Pokémon, and the number of the same Nature has dropped to less than 20. The current situation is so different from the previous one that I think there is a bug. By the way, after landing today, only one of the 10 Mawiles caught has the same Nature. I mean, even though I am quite unlucky, it has already made me doubt.