Events+ attendance not showing as "paid" in event RSVPs

When PayPal is set to "Live" mode in Events+, users who RSVP and pay for the event are shown as "Not paid" in the RSVPs section in the admin-side editor of the event, even though the money & transaction does appear in my PayPal account. Curiously, when PayPal is set to "sandbox" mode, it works just fine and paid users show as "Paid" in the RSVPs section as expected.

On another note, during much troubleshooting with Patrick, we discovered that it was the presence of RSVPs in the event reported in the following thread that was preventing that event from being edited, but only if the Membership Integration addon was active in Events+. https://premium.wpmudev.org/forums/topic/conflict-with-events-membership

Once all RSVPs had been deleted from that event, it can be edited again. Could these 2 issues possibly be related somehow?