Hikvision DS-7604NI-E1 DVR live stram fails with error:
Note: Live view failed.
The issue only affects the live view. Recorded videos and other web interface components are working fine.
Hikvision DS-7604NI-E1 is one of those older CCTV DVRs that only work in Internet Explorer as it requires an Active-X type plugin (WebVideoActiveX Control installed via WebComponents.exe)
After a bit of experimenting, I narrowed down the issue to Sophos Endpoint Advanced antivirus product. After a few back and forths with Sophos technical support, they confirmed that this was a bug which will be fixed in 2022.1 update. I also noticed that the issue didn't affect older builds of Windows 10 (i.e. 20H2)
Although Sophos didn't provide an official workaround, I found that disabling the "Network Threat Protection" module allows to temporarily view the live stream.
Windows 10 Pro (21H2)
Sophos Endpoint Advanced 10.8.11.4
Sophos Intercept X 2.0.24
Hikvision DS-7604NI-E1 DVR