Reported in OTRS for 2.6.198-r-2017-06-09:
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=10091234
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=10097056
as well as in many negative Play Store reviews.