Subscription refund: Stripe Refunds API Charge ID or Payment Intent missing

That's exactly what I thought to observe yesterday, when trying to figure out what could make the difference between py_ and ch_ records. I miss of course your knowledge, so thought it didn't make sense to mention it.
See newly attached screenshots.

Yeah, the non-card payments are using py_, but it's not documented in their documentation. From all that I can find they should be treated same as charges so refunding them is trivial, but I've reached out to Stripe developer support to get some confirmation.

Ok, was able to confirm py_ payments should be treated as charge objects. Have fixed and confirmed refunds for them. Once the fix is merged we'll have a new CBSubs build release available with this fixed.

Ok, new CBSubs build release is now available. You should be able to refund py_ payments just fine now.

thank you for the quick investigation and fix!
I will download/install the fix right now and will give you feedback once I had done one refund. Might take a while, as we just started the registrations for our sports tournament and participants usually have to cancel their participation only after a while, if any.

Unexpectedly, I had to do a refund a payment with a py_ record this morning, and can confirm it works now again as expected. 
You may consider this issue as resolved as far as I am concerned.
Thank you very much for the quick resolution!