Pokémon Masters EX is currently dealing with two newly identified issues affecting some players. The first prevents progress after a fresh installation, with the game halting at the Pokémon Center screen and becoming unplayable. The second causes the app to force close under certain conditions when attempting to enter a co-op battle. The development team has acknowledged the problems and is expected to provide updates as fixes are prepared. In the meantime, affected players may need to wait for a patch before normal play resumes.
Source: Official Pokémon Masters EX site
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