Sorry it's taken me so long to get back.
In order to fix the problem, I had to both disable Game Launcher and also run Game Tuner; for this to work, in Game Tuner, I had to go to MODES and select "Maximum Quality", which forced Simcity Buildit to launch in the best resolution that my phone supports. Until I'd done this, simply disabling Game Launcher didn't work.
No problems since then (although I've no idea if EA have fixed this issue in the last couple updates, but I am not going to find out and will just stick to the above regardless...)
So yeh, this is a work around that seems to solve the problem but point out that it's really not acceptable that we both disable one third party app and download and use another third party app to fix this.
