Using the Analysis widget with a custom web tool in ArcGIS Experience Builder causes tool parameters to reset to default values when clicking the 'Draw input features' button.
This issue is not reproducible in ArcGIS Enterprise 11.4 or newer. A recommendation is to upgrade.
If a fix in ArcGIS Enterprise 11.3 is required, please work with Esri Support Services to submit a hotfix request for the released ArcGIS Enterprise version.
解决办法
Input the drawn feature first, then fill in the tool parameters.