I'm now convinced that I have run into a bug, probably in cTtrader. I have already been engaged with Pepperstone support and have completely uninstalled/reinstalled cTrader and cAlgo including the .NET framework as requested and there are still issues. I have narrowed it down to a set of steps to reproduce.
1. Make sure there is only one chart open in cTrader and close it
2. Clear my cTrader cache
3. Open cTrader, everything looks normal and this my reference point
4. This is what kills it. Open the same symbol chart with the same timeframe again and the volume and wick of the active candle gets corrupted ON BOTH CHARTS:
5. Opening a 3rd chart with the same symbol and the same timeframe causes the volume to get further corrupted on all 3 charts:
Opening up a chart with another symbol or another timeframe does not cause this issue. These same steps also cause the issue in cAlgo.
It does not appear to be related to the chart only. It seems loading the same MarketSeries twice is causing the issue. I have replicated it where the first tab contains a market scanning tool which has loaded AUDUSD 8h MarketSeries using MarketData.GetSeries(...) while the root chart is EURUSD - opening a second tab that is a native AUDUSD chart manifests the same issue.