I have the same issue:
DH_NVR4XXX-4KS2_MultiLang_V4.001.0000000.1.R.200319:
Alarm events can be reported but IVS Search does not produce anything
DH_NVR4XXX-4KS2_MultiLang_V4.001.0000003.1.R.200813 & DH_NVR4XXX-4KS2_MultiLang_V4.001.0000005.1.R.201126:
Alarm-reporting and IVS-search are also...