I've had the same problem and on mine it was relay. I also tried everything but after replacing it with (non-Suzuki) new relay, specific for LED turning signals, it's all good. The only difference, that I can notice only at night, is that the indicators on the dash don't turn off completely while using the turning signals, but the turning signals themselves work very good.
Suzuki relays (for their LED turning signals) are known to fail after a while.
2017 DL1000 White
2014 DL1000 Red (sold)
2012 DL650 White (sold)