4028 Fan not running below 50% on SKR Pro 1.2

Hi! Just installed my new 4028 Fan on my printer, but it isn´t working below 50%. Additionally, between 50% and 99% everything seems like a normal increase of speed, but the last 1% gives a big increase in speed and SOUND! Then, at 100% the fan starts to pulsate strangely. I managed to get the tachometer running and it also indicates the strange behaviour. At 99% it measures a propper speed, but at 100% it´s showing a red zero (picture)! Fan: Delta FFB0412UHN-SM36 bought from Rat Rig. Board: SKR Pro 1.2 I connected the Fan according to the Rat Rig Guide.

printer.cfg