The data resolution does not affect whether or not you're seeing candles.
If you don't see closing prices, it's because the resolution of your chart view is too fine. On line #34, you can see we are only plotting the closing price. So if our chart is zoomed in such that one point per day is shown, it will only show a "line" (i.e. a candle where O=H=L=C).
Let me show you an example. Please change the range of your backtest so you have at least 1-2 years between the start and end dates.
Image #1 - daily data, but I'm zoomed in, so the charting engine will show me one point per day:
https://user-images.githubusercontent.com/4928988/57196528-a7d26e80-6f55-11e9-891d-93137d78277f.PNG
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Image #2 - daily data (again) but now I've zoomed out. The charting engine shows me one point per week which means each candle will now be composed of 5 days' worth of data. O, H, L and C will be generated from the closes you've provided:
https://user-images.githubusercontent.com/4928988/57196547-d2bcc280-6f55-11e9-8322-3e9d6608afe6.PNG