No time slider after export from ArcGIS to WebMap

Question

All attempts to export a map with time slider from ArcGIS Pro to WebMap failed. I do not know what else I can do 
 – do you have any idea how the slider can be displayed in the webmap?

THANKS!

In ArcGIS Pro: Map with timeslider

After sharing in ArcGIS Pro to Webmap: No timeslider - and no possibility to add

MatthiasKöhler · Answer

One addition: Now I also tried to load the map in the "WebApp Builder" and add the timeslider widget there – then the error occurs that no time data was detected.