New subsciber here with the 10 GB plan, had service established and installed at our cabin on May 18, used it while we were staying there until we left on May 20. Subsequently, looking at the usage page, hovering the cursor over each of those days on the graph and noting what our daily usage was and then doing the math it shows we used 3.8 GB in those 2.5 days. But the usage page currently shows we used 0 GB still have 10 GB available, I'm guessing that is has something to do with the 20 day replinishment period?
Also, regarding the graph, it's my understanding it shows what data is remaining rather than what was used. On May 20 the graph drops to zero and at the bottom it says we have 0 MB remining ... we only used 3.8 GB, why the descrepency with the usage page? I should note that we turn the power off when we are not saying there as we did when we left on May 20. Does that have anything to do with how the graph obtains its information?
Regarding the page currently showing 0GB of usage, it's because of the 20 days of data replenishment, like you mentioned.
With regard to the data graph showing 0MB remaining, the graph staying up to date is dependant on the modem itself, so if the modem has no power the graph will show what it presently is when looking at it remotely, like when signing into the site or using the mobile app. When the modem is powered and the connection is reestablished it will update the graph to current. The graph can also get a little "kooky" during the 20 day data replenishment period, so even if you were using the system every day the graph itself would still look funny during this time. The usage shown when you hover over each day would be correct, but the graph itself would always either look full, or almost full, depending on when it updated. Once the twenty days are over the graph will reflect the normal usage, but it is still dependent on power, so if you regularly turn the power off it again may not look right until the power is turned back on and the connection is reestablished.
Also, just so you are aware, there may be times when you remotely look at your data and it hasn't reset for the month. This is because, like the graph, your data performing its monthly reset it dependant on the modem being being powered and connected. So, say you left your cabin and turned the power off on day 28 of your monthly data cycle. The data remaining will stay at the same level, whether it's a day, a week, a month, or even a few months, until the modem is powered again and the connection is reestablished. And, if it's in a new data month, the data will reset when that happens.
Hope this helps.