After troubleshooting with the customer's process provided in the support case, we figured out it is related to the field in the table is set as read-only using field properties, you will run into the issue if Task in table is set to read-only with following lookup rules configuration.

The workaround is to uncheck the read-only from field properties and use custom JavaScript as following to set the field as read-only(scenarioTask is the CSS class configured for Task field):

$(document).on('lookupcomplete', function(event){

  $('.scenarioTask input').prop('readonly', true);

});