Magento 2 Schedule Status Suspended – How to Resolve

Try

0 0,4,8,12,16,20 * * *

Note, if you do not see the cron in the table, it's not an error, because the scheduler creates the record with some delay.

Magento can increase the memory for processing a large amount of data by using memory engines instead of InnoDB. The algorithm increases the memory value for the max_heap_table_size and tmp_table_size MySQL parameters.

When the allocated memory size for a temporary table will be greater than 20% of innodb_buffer_pool_size, the error message is written to the Magento log.

To prevent this error message, you need to update default Batching configuration of catalog_category_product (Category Products) indexer because "Current batch size: 100000".

For more details, take a look here.

Try following code:

app/code/[VendorName]/[ModuleName]/etc/adminhtml/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Catalog\Model\Indexer\Category\Product\Action\Full">
        <arguments>
            <argument name="batchRowsCount" xsi:type="array">
                <item name="configurable" xsi:type="number">100000</item>
            </argument>
        </arguments>
    </type>
</config>

Note: Decrease the batchRowsCount to resolve the error.