Does data just disappear?

I've been running some backtests using bid/ask/last tick data and suddenly the 'last' tick data series is missing 8 trading days. I confirmed by using Historical Data Manager and I tried reloading the database but the data is "missing". I've tried restarting NT, too, but can't find the missing data.

Any ideas on where to look or can it literally just get deleted out of the database by itself?

Who are you connected to? (This is indicated in green in the lower left corner of the Control Center)

What instrument are you attempting to load?

What expiry are you using with this instrument?

Are there any errors in the Log tab of the Control Center?

Not connected to any data vendor. This is my research PC. The missing data is 6E continuous contract data from the 1st week of 2013. There are no errors in the log. The bid and ask series are there. The Last series was there up until about an hour ago.

If you are not connected to anyone for data, where are you expecting this data to come from?

NinjaTrader will not remove previously downloaded historical data unless you are connected to a datafeed and trying to reload all historical data and the data feed does not have the data.

No, it is not expected that if you are not connected to any connection, that historical data would be deleted from NinjaTrader unless this was deleted on purpose from the Historical Data Manager or from the Documents\NinjaTrader 7\db\tick folder.

The only time NinjaTrader will remove data automatically, is when reloading data and about to replace this with newly downloaded data from the server.