Everything worked well - no one warning or error message.
After rebooting the device all things looked well - BUT the SIM card isn’t detected. Before flashing to eOS the SIM card worked without problems. And I tried with an other SIM card of an other provider - same problem.
SIM card has password check switched of. I did the flashing a second time - no change.
There are only a few entries in the list. Seems that is any connection to the SIM card. IMEI unknown, but SIM seems to be ok - checked with an other smartphone.