Ion-datetime [min] doesn't refresh

Hello guys, I’m using ionic 4 and I have two pickers. The 2nd picker is “dependent” from the 1st one because the 1st one is the begin and the 2nd is the end. I wanted the 2nd picker to start at the date of the 1st picker. it works in the first time because the 1st picker is always filled, but when i change the first picker again, the date wont update. the min is alright, but the default value is not the min date and can lead to mistakes. how can I fix this? thank you