Store credit wrongly calculated?

Hi,
promising plugin!

While testing I noticed that the store credit seems to be wrongly calculated:

1. Manually created Referral, amount: $15
   Switched “Mark as Paid”/”Mark as Unpaid” a few times (don’t know if this matters)
2. Created a second Referral for the same Affiliate as in 1, amount: $80
   Marked as Paid
3. Logged in as the Affiliate, was offered a Store Credit about -15$ (minus?!)
   Shouldn’t it be $95?
4. Deleted all Referrals (via UI) and Payouts (manually in DB, table [prefix]_affiliate_wp_payouts)
5. Created a new Referral by completing a WooCommerce order as a different user, amount: $10
6. Logged in as the Affiliate, was offered a Store Credit about 75$
   Shouldn’t it be $10?

I’m quite confused about this. Is there some kind of caching active?

Any feedback/hints or help is greatly appreciated!
Thanks!

PS: I was not sure where to post this question. If you want, I can create a GitHub issue as well.