On one of my systems I am getting kext loading errors due to "Kext rejected due to improper filesystem permissions:"
They are 755 all the way and owned by root:wheel. Never had that before. It impacts one of ours. The same install works fine on another system.
What OS version are you having the problems on? I had a similar problem on 10.13 and it turned out the system was checking permissions on the copy of the kext inside /Library/StagedExtensions/Library/Extension not the one inside /Library/Extensions and for some reason it would not sync the two. This staging of kext's is part of the new kext consent "feature" added to High Sierra. You will need to boot to recovery mode or another OS to remove the bad copy in /Library/StagedExtension since it seems to be protected by SIP.