XIAO: DCF77 library not working


i use the DCF77 library on an Arduino Nano and it works great. When I try to use it on an Seeeduino XIAO, I get no time update.
With the example sketch “DCFSignal” I can see the correct incomming signal. If I use the sketch “InternalClockSync” the time is never been updated.

DCF77 library: https://github.com/thijse/Arduino-DCF77

With this Sketch https://forum.arduino.cc/t/yadcf77-yet-another-dcf77-sketch/215758 i get the correct Date and Time after 2 minutes.
Also the Sketches from https://wolles-elektronikkiste.de/dcf77-funkuhr works.