Left side of my graph is empty, X-Axis not scaling automatically

first up: I’m not a SQL/GRAFANA/DATA expert, so please be patient with me.
I got grafana up and running and have data displayed.
However: I was surprised to see the left side of my graphs always empty, so I did a little google-ing and digging but couldn’t find a solution.

I write various sensor data into a MySQL DB.
All timestamps are UTC+0200

As you can see, the left side empty. The time range to be displayed is “now-2d” to “now”.
What confuses me is that the marker is clearly at 09/30 ~09:00 but the corresponding dataset retrieved for that point states “2020-10-01 01:00:01” (which is correct, as I want to see the data of the last 2 Days)
Why is my x-axis not adjusting automatically ?

My SQL query
UNIX_TIMESTAMP(CONCAT(Date,’ ‘,Time)) as time_sec,
Download as Download
$__timeFilter(CONCAT(Date,’ ‘,Time))
ORDER BY CONCAT(Date,’ ',Time) ASC;”

If I change the time range to (e.g.) “now-6h” to “now”, the entire graph is empty and all I see is a message “no data” (which is not true, as there is data available).

The query options (Min Interval) are adjusted to the write frequency of the sensordata (in this case, 2h).
Any tips, ideas are much appreciated.