We hope to increase that limit in the future. The dashed blue line that appears on intraday charts represents the closing price for the previous trading day. I can't seem to use some of the indicators or price overlays when I am viewing an intraday chart. There are a number of our indicators and price overlays that do not work well with intraday charts because of the way they are calculated. Because they depend on the ZigZag indicator, Price Labels are also disabled.
Dashes appear on our intraday charts if there was a gap in trading activity for that period.
These large discrepancies are usually caused by an erroneous trade being recorded. These errors are usually removed after the market closes, so they do not effect the next day's chart. All indicators that are used in SharpCharts are calculated using 'Periods'. Since we do not provide that much historical intraday data, the MA line would disappear. To get your settings to reappear you may want to change the period with which they are calculated.