The max amps is set by the plug adapter you installed in your UMC. A Schuko is rated for a maximum of 16A, but Tesla derates to 80% of the plug rating for safety (as required in many countries). So a Schuko will normally top out around 13A, not the 32A of a USA 14-50. So that 8A is not far off from the max it should select. Try looking up the Tesla specs on the exact plug adapter you are using: that is most likely what is happening.
Also, what voltage is the plug displaying on your Tesla screen? Tesla further degrades the current if the voltage is low.