I have had the same problem for months, although the unplanned charges seem to be relatively small.
The Inverter Page Meter Data option has Grid to Battery data at 5 minute intervals but the values are cumulatives, so difficult to get any quick idea of the times and amounts of the unplanned charges Grid to Battery.
The Inverter Page Meter Data shows Battery OUT totals, but no breakdown - Battery to Home / Battery to Grid.
The Dashboard Page has a directly downloadable daily activity report, that shows more clearly, but at 30 minutes intervals, the KWh values of both Grid to Battery and Battery to Grid.
If you look at these you will also notice that there are much higher amounts showing as Battery to Grid, another unplanned activity.
This is mostly a times when there is not similar unplanned Grid to Battery charges, so unlikely to be any "battery smoothing" ins and outs, and potentially a direct loss of paid for Grid to Battery charges.
My set cheap rate period is 04:45 to 08:05 - part of Economy 7 Summer Time cheap rate - and this Dashboard Page report is showing the activity as 03:45 to 07:05 - part of the Economy 7 Winter Time cheap rate.
I would be interested if you have the same display problem.
The downside is that GE tech have no idea why there are these unplanned Grid to Battery / Battery to Gid movements, or why the Dashboard download is showing incorrect dates.
Not sure if this is necessarily helpful, but at least it shows this is not just a problem for you.
Cheers