I have many epics with sub-issues (tasks, bugs, stories) that are not being displayed in the 'Progress (issue count)' field at all.

Here's an example of an epic whose sub-issues are not being displayed in the progress (issue count) field at all.
To be fair, it's 189 sub-issues. Is there a limit to have many issues in an epic is supported by the 'Progress (issue count)' field?
If not, how can I create a custom field that does take all epic sub-issues into account? (so what this field is supposed to do, but actually do it)
Using Atlassian Jira Project Management Software (v9.4.4)