Hello Sascha,
Is the issue occurring for only address data or any other data set as well like Name, Communication data etc.
Since the issue is random i can't be sure why replication doesn't works. It's better if you debug below FM during change in XD02.
1:- Program SAPLCCCO routine START_DOWNLOAD (check whether the filters are ok here or not)
2:- FM PI_BP_MAIN_TO_BAPIMTCS check complex structure contains correct data or not and conversion to BAPIMTCS happens.
3:- FM CRS_SEND_TO_SERVER check whether correct BAPIMTCS reaches till this function module or not.
Let me know what you find after debugging.
Best Regards,
Rahul Singh Parihar