Essentially GMT brokers will get the first part (3 hours currently) of the Sydney open at the end of the day - where AUD has some volatility, whereas that is the start of the day for GMT+3 brokers. At the end of each day the "daily line" is completed so even though the price is a reflection of previous periods it also will be affected by the last part of the "day" and what was missed in the first 3 hours of the starting period. I hope that makes some sense.
Could that cause the disparity?
I will just monitor both and see what suits.
btw I tried turning Ignore Sunday bars or whatever it is called on/off and it made no difference today - maybe it would earlier in the week when it might have a larger % impact.....then again not much usually happens on a Sunday AND the price will still have moved the same amount from the Friday close if it is just ignored and the indi starts from Monday - just over a slightly shorter period for averaging.
Cheers,
Dave.