First, try to index the out-of-sync item using the SKU re-indexing form.This tool is useful to check if your products meet all the requirements to be indexed in the Algolia’s indices. And if not, the tool will tell you immediately the reason why the products are not indexed. You can find more information on the indexable products criteria here.
If you see the error message 'Record is too big', you can refer to this troubleshooting guide here.
For a more detailed troubleshooting guide, we recommend reviewing this documentation on "out of sync data".