Rule 5 Draft in Historical Play
 

The option to enable the Rule 5 draft in historical play with reserve clause era rules is ticked, however I am getting no population in said draft. When filtering for eligibility I do get a lot of players that are eligible. (see screenshots)

The wiki for OOTP 25 lists the following: Note: Rule 5 drafts can only be enabled in leagues that have affiliated minor leagues! If you don't see this option, you might not have any minor leagues associated with the currently selected league.

I am currently in the 1917-1918 offseason, with multiple independent minor leagues but no teams affiliated to major league teams yet as per history. Would this be the cause for the draft not populating?

Yes the minor league teams would need to be affiliated to an MLB team, since the rule 5 draft is for spreading out talent, and keep teams from blocking layer path to the majors. talent. For this reason I shut it off in my league.