Why modification done in a workflow are not reflected in Lucene AOD search result?

We have Version 7.11.18 (in linux/apache)

We created a custom module, this module has a name field and a description field. Its records correctly ends up in lucene search (Advanced Search).

When we change a record, changes are reflected in lucene search, as expected, but

when we change a record with a WorkFlow, then lucene search is never updated at all: is this normal?

In details, we have a custom module, called workcode

workcode.name
workcode.description

we updated the name with a WorkFlow on_save

We guess that when we modify by hand (with the GUI), then something tells lucene to update results, while this is not triggered when the modification are done in a workflow, which is what we would like.

How can we solve it?