@whatisglutathione I had the following response yesterday…
The issue you are encountering is a known issue to us and we have a bug open for this. Last week I reviewed some reports and it seems that this might not have been caused by the plugin, but possibly by the server side of PayPal, since the issue occurs in 1.6, 1.7 and 1.8 (as far as we tested).
We have asked PayPal to take a look into this, and are pending their response. I have linked this thread to the bug, so you should get an update when we have a fix or workaround available for you.