Helper bash script which you can use to run wp all import synchronously. This also outputs problems which you may have with wpai.

wpai-run-imports.sh

#!/bin/bash
##
# Script to run WP All Import scripts sychronously with cron
##

# This is default wp core directory for us
ABSPATH="/var/www/project/wp"

function usage()
{
    echo "wpai-run-import"
    echo "- scipt to run WP All Import triggers synchronously"
    echo ""
    echo "Parameters:"
    echo "WP All Import key:"
    echo "--import_key=xxxxyyy"
    echo ""
    echo "WP All Import jobs:"
    echo "--import_ids=1,2,3,4"
    echo ""
    echo "WP Core path:"
    echo "--path=/path/to/wp/core"
    echo ""
    echo "Example:"
    echo "$0 --path=/data/code/web/wp/ --import_key=xxxxx --import_ids=16,14"
    echo ""
}

##
# Parse all flags
##
while [ "$1" != "" ]; do
    PARAM=`echo $1 | awk -F= '{print $1}'`
    VALUE=`echo $1 | awk -F= '{print $2}'`
    case $PARAM in
        -h | --help)
            usage
            exit
            ;;
        --path)
            ABSPATH=$VALUE
            ;;
        --import_key)
            IMPORT_KEY=$VALUE
            ;;
        --import_ids)
            IMPORT_IDS=$VALUE
            ;;
        *)
            echo "ERROR: unknown parameter \"$PARAM\""
            usage
            exit 1
            ;;
    esac
    shift
done

##
# Run all imports
##
for import_id in $(echo $IMPORT_IDS | sed "s/,/ /g")
do
    echo "INFO: Running import with id: $import_id"

    # Start import
    echo -n $(date +"%d/%m/%y %T > ");
    php -e -r "parse_str('import_key=$IMPORT_KEY&import_id=$import_id&action=trigger', \$_GET); include '$ABSPATH/wp-cron.php';"

    # Wait until importer is ready
    errors="0"
    wait_seconds="20"
    while [ $errors -lt 5 ]; do

        # Get importer status
        importer_result=$(php -e -r "parse_str('import_key=$IMPORT_KEY&import_id=$import_id&action=processing', \$_GET); include '$ABSPATH/wp-cron.php';")

        # Output time for better logs
        echo ""
        echo -n $(date +"%d/%m/%y %T > ");
        if [ "$importer_result" == "" ]; then
            errors=$[$errors+1]
        elif echo $importer_result | grep '"status":200' | grep 'Import' | grep 'complete'; then
            break
        elif echo $importer_result | grep '"status":403' | grep 'is not triggered'; then
            # 403 could mean "already processing."
            errors=$[$errors+2] # Stop sooner if we get these messages twice
            sleep $wait_seconds
        elif echo $importer_result | grep '"status":500'; then
            errors=$[$errors+1]
            sleep $wait_seconds
        else
            echo $importer_result
            sleep $wait_seconds
        fi

        # Increase waiting time with each loop so that we can create smaller logs
        wait_seconds=$[$wait_seconds+20]
    done

    if [ $errors -lt 5 ]; then
        echo "ERROR: Aborting import $import_id after 5 errors..."
    fi
done