Index – ready but 11619 in backlog

We have a indexer in Magento 2.3.3 that is giving us a difficult time.

We tried many times reset and reindex that indexer but does not help.

| Bol.com Offer Export        | Ready            | Schedule  | idle (11619 in backlog) | 2020-01-18 19:31:42 |

So this is from extension https://marketplace.magento.com/honl-bol-com-retailer.html

We tried many times
php bin/magento indexer:reset bol_offer_export
and then
php bin/magento indexer:reindex bol_offer_export

But no luck at all. Any ideas on this?