I know you said you've done both, but let's re-trace our steps so we can get this working for you from a fresh perspective:
Download the mass markings you're wanting and place the download on your desktop.
Go into Local Disk (C:) \\ Feral Heart and delete the markings.cfg, then replace it with the markings.cfg found in your markings download.
Go into Local Disk (C:) \\ Feral Heart \\ Media \\ Textures \\ Markings and delete everything in there, then place the .png files from the markings download in there- just so everything is fresh, so you can be absolutely sure.
Relaunch Feral Heart (if you're in-game already).
One thing I once found is that I accidentally placed things into a backup Feral Heart folder I had by mistake, leaving me wondering why things weren't working like a dumb dumb.
Could be a long shot, but maybe this is happening to you too.