Hi all,
my solution is quite primitive, but unfortunately don't have enough time to fully explore the reason of this bug. Will appreciate if anybody will do some research...
Ok, let's go:
1. Open "flotr.js" file and find the line with "isIphone: /iphone/i.test(navigator.userAgent),",
2. Now simply change it on "isIphone: false,"
That's it! Now the chart will work ;-)
Best wishes.