Hyperpixel 4 square touch offset

I have a RB 2 Model B with a Hyperpixel 4 square.
First problem I had was that the mouse on the touchscreen was inverted. This I solved by inverting the creen configuration settings.

But I still the touch has an offset of about 50 pixels to the right and bottom.

I tried calibration with ts_calibrate. In ts_test I was able to drag the cross hair accurately and drawing works like a charm. But as soon as I exit the ts_test app and return to the RB desktop the touch is again off with about 50 pixels.

Hope anybody can help.

Below my config.txt settings:
[all]

dtoverlay=vc4-kms-dpi-hyperpixel4sq
dtoverlay=hyperpixel4sq
dtparam=touchscreen-swapped-x-y=1
display_rotate=2

overscan_left=0
overscan_right=0
overscan_top=0
overscan_bottom=0
framebuffer_width=720
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x7f226
hdmi_timings=720 0 15 15 15 720 0 10 10 10 0 0 0 60 0 35113500 6