Round Trip Sensort fails "Helo command rejected: need fully-qualified hostname"

Since 22.2.77 roundtrip sensor doesn't work properly:

Sending Mail: <MyPrtgMachineName>: Helo command rejected: need fully-qualified hostname
I set a correct HELO identifier in the mail-setup of prtg (https://myprtgserver/systemsetup.htm?tabid=3) and in the round trip sensor. But it seems a change that came with the latest update forces the mail-part of PRTG to use my windows machine name as HELO identifier and uses a non-fqdn-version of that.