Every site that I've talked to has had issues with 1709 in one form or fashion. 1803 has shown to cause less issues and headaches. I again strongly recommend that you cancel 1709 and push for 1803 to be deployed instead.
Additionally some sites reported random issues like they had to update their client's drivers for Patch 11 though if you used the October removal tool (or removed all McAfee products and registry keys) and the reinstall didn't work I don't know what to tell you. You might have to pay for support...
ENS, go to ENS.!
Also, I am baffled by the comment that you have no vendor support. If you have a license you have support.
Which version of the Endpoint Product Removal tool did you use? ePO_ProductRemovalTool_18.104.22.168 actually fixed the issue of needing to manually remove registry keys in Safe Mode after running the removal tool. If you don't have the latest removal tool then I would recommend removing everything McAfee, reboot, reboot into Safe Mode, remove all McAfee* and MFE* keys (especially from Root), reboot and then perform clean installs of the updated versions, installing MA first and HIPS last.
1803 is not an option. We have ProductRemovalTool_22.214.171.124 and it has not made any difference from the older version as far as this issue. Keep in mind these are 1703 systems that are having this issues, they have not been migrated to 1709 yet.