Mail POP3 problems since update to v8.7.4

Dear members! Since update from 8.6.15 to 8.7.4 I can´t receive pop3 mails. I get this error-massage: WARNING - *EmailImport* : Error getting number of messages from pop.ionos.de as tr@xxxx-xxxxxvermittlung.de for user Thomas

IMAP works, but there is the problem, that all incomming mails are marked as read. In the system the automatic read marking is disabled. My mail-provider will not see a problem an with MS and Apple clients is no problem receiving the mails from pop3