Importing Vendor Payments is working fine until I do it with a particular User Event script. The scripts function is to populate the Payment memo with a summary of the Bill references. Problem is that some imported Payments will be saved with blank document numbers (tranid). The UE script has been working fine in the UI for a year. The UE script does not access the 'tranid' except I've added it now for debug purposes. From the debug logs the transaction already has a blank tranid as soon as the script executes whereas for the transactions where it works correctly the tranid is immediately present.

if (context.type !== context.UserEventType.CREATE && context.type !== context.UserEventType.EDIT) {
      return; // Only run on creation or editing of Vendor Payment record
    }
    
    var newRecord = context.newRecord;
    var vendorPaymentMemo = '';
    var paidBills = [];
    
    // Get the paid vendor bills linked to this vendor payment
    var lineCount = newRecord.getLineCount({ sublistId: 'apply' });
    for (var i = 0; i < lineCount; i++) {
      if (newRecord.getSublistValue({ sublistId: 'apply', fieldId: 'apply', line: i })) {
        var paidBill = newRecord.getSublistValue({ sublistId: 'apply', fieldId: 'doc', line: i });
        if (paidBill && paidBills.indexOf(paidBill) === -1) {
          paidBills.push(paidBill);
        }
      }
    }
        
    // If paid bills were found, construct the vendor payment memo
    if (paidBills.length > 0) {
      var billSearch = search.create({
    	  type: search.Type.VENDOR_BILL,
    	  filters: [['internalid', 'anyof', paidBills],'AND',
    	            ['mainline', 'is', 'T']],
        	columns: ['tranid']
      });
      
      var results = billSearch.run().getRange({ start: 0, end: 1000 }); // Limit to 1000 bills
      
      for (var i = 0; i < results.length; i++) {
        vendorPaymentMemo += results[i].getValue({ name: 'tranid' }) + ', ';
      }
      
      vendorPaymentMemo = vendorPaymentMemo.slice(0, -2) // Remove the final ', ' 
      
    // Set the vendor payment memo
    newRecord.setValue({ fieldId: 'memo', value: vendorPaymentMemo });

very weird. maybe share it to #C29HQS63G?