It is surprising that it has been over 2+ years and yet Sony has been unable to solve this problem. On this forums - there're a few comments from Sony representatives, dated about a year back, mentioning that the USM issue will be solved over the next update. I'm using the latest Z5 phone, which is less than 3 months old - and now stuck with the same problem (activating USM wipes out all apps and corrupts Google Play Services). If this feature is a known issue - why is it provided in the phone. From Z2 to Z5 - all sony phones suffer from this problem. All threads on Sony forum relating to USM issue point to this thread - but in the end, its an unsolved problem for which Sony has no answer.
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