The amber triangle with an exclamation mark therein is a standard warning indicator. Mine goes off for low fuel, but also if my TPM senses low pressure, or I assume if any other fault occurs that would require the rider's immediate attention.
I have heard of one or two cases of transmission failure of the GT, but that's pretty rare overall.
As for the clanking noise on startup or at idle, that is often the cam chain tensioner not getting enough oil pressure to take up the slack. It may be common but it is not
normal, it will
get worse over time, and there is
a known fix for it, including an official BMW Service Bulletin with an upgraded cam chain tensioner.
It sucks that you're still finding teething issues on a bike that's been in production for 3 years now (and the engine longer than that). But when these bikes do run properly, there's nothing else out there that can touch them.
Anyway, I hope they find your problem and get you sorted and back on the road soon.
'13 Dark Graphite Metallic K16GTLD, 24K miles and counting...
'09 Magnesium Beige Metallic K13GT, 60K miles miles and counting...
'02 Mauve Metallic K12LTC, 106K miles and sold
BMWLT#145, IBA# 366, MOA# 111996, SCMA# 24032
All lower 48 states plus Alaska on the K13GT in two weeks . . .
Some people see the gas tank as half empty. Some see it as half full. All I care is that I know where the next tankful is coming from...