After a certain amount of time, the randomizer challenge will stop taking effect. It might occur after fighting an unrandomized trainer a number of times (dexnav trainers, level trainer, etc.) Version is 1.2.3. This bug occured on my mac, so it might just be affected in only on mac. The screenshot I attached depicts a level 47 Palkia against a level 44 Dodrio owned by a Sky cultist, because I felt the need to attach it.
Issue #2545 new