I'm trying to create a rule that only replies to the sender, but the
choice always reverts to "Reply to All."

"Reply to All" is the default when I select "Add Action", "Reply..."
in the rule actions section and even though I select "Reply to Sender"
it reverts to "Reply to All" after I save it.

How can I add an action that only replies to sender?

Client is XP SP3 + GW 8.01 HP1