PDQ Inventory unable to scan new computers added to domain.

We've been experiencing some strangeness with Inventory for the past 1.5-2 weeks.

When adding a new computer object to our domain, PDQ won't automatically 'see' it. This in itself isn't ideal, but is fine as we just manually run an AD sync and then PDQ will 'see' that the object exists. However, from anywhere from 30 minutes to an entire workday (9hours) PDQ will NOT detect that the target machine is online, so it can't install Agent etc. It's as though PDQ is 'reaching out' to these machines, and the machines are 'talking back,' but PDQ is not getting that communication. This has been happening for roughly a week and a half, which is when we updated to the most recent patch of Win10 (17763.379) and WinServ2016 (14393.2848).

Manually installing Agent does not work, even with the custom XML that PDQ recommends for machines that have not yet been scanned. Flushing DNS does not work. Restarting target machine does not work. Restarting Inventory service does not work. WoL does not work, even when manually adding target machine's MAC address. There doesn't seem to be any real rhyme or reason to when Inventory finally does decide to 'communicate' with the target machine - it can take half an hour or hours, and it was previously done in under ten minutes.

Has anyone else experienced issues like this since the latest patch? Or issues like this in general?

also, I'm recreating this process with a target machine that is 'out of date' by a few patches and I'm seeing the same issue.