Here's an example that happened early this morning while I was trying to get the VK9NC Norfolk Island DXpedition on their first day.

After 2 hours of trying to get through a huge pileup I finally got them but then all of my RR73 apparently were not working even though he was hearing me at -9  and I was receiving him at -1 to +1. I kept sending RR73 but he wasn't getting them.  I lost out on an ATNO. But then I tried a few minutes later and got him (see pic 2). This dropout started after the last upgrade.