IB data is completely useless. Like mentioned here
during market hours it is almost impossible to get data. So if you plan to add a
symbol during market hours forget about it.
I experienced that my internet connection went
offline and when it returned to the online status I could not backfill the data
for that day even though it said that the data had been backfilled. So the data
for POT for that day where gone and I could not backfill them during market
hours. Luckily I also use IQFeed but I used to use IB data to execute the
systems. Seems the quality is getting worse each day.