I am using the standard version from retroarch out of the shield playstore. Before i made the update from shield firmware 6.3 to 7.2.1 i had no issues with the controller in retroarch. There are only these probs in retroarch.
Edit: i found out, that these problems had something to do with the frontent i am using to select the games with… its the App “Dig”… a very nice frontend like gamesome to load games from. Inside the options there, was a setting activated with reset Retrarch settings each time… after deactivating this, it works again as it should… start+select to open menu.