After extra delay we tried again with the updated Agent 5.6:
- Agent deploy via ePO was successful;
- VSE deploy via ePO was successful, however the DAT remained 1111 and didn't update (ePO was used to initiate DAT update);
- After OS reboot the DAT was updated to actual version;
- Now we have to monitor fully automatic DAT update process. If at Monday DAT will actualize, the issue should be considered as solved.
Yes! Complete success:
- The update is stable;
- Another system with similar symptomatic was processed in the same way (Agent uninstall - McAfee products removal tool - Reboot - Agent deploy via ePO - VSE deploy via ePO - Reboot - DAT update), and result was the same. System also updates regularly.
Seems the issue was caused not by agent 5.5 only, but to remove that issue a single component change is enough. Great thanks to Everyone involved!
Just in the past week I have had the updater problem return on one of the Exchange servers that I had previously fixed. DAT updates stopped once KB4493446 was installed. I've asked our Exchange admins if we can remove that KB in order to see if that fixes the problem.