KBFS is not working on either of my macs (work and personal)

Keybase has not been loading the private filesystem on my Mac (running Catalina) and I'm not sure why. I got this error from the GUI today. I have neither VMWare nor VirtualBox installed on my system, although there is a Cisco VPN installed. By the way, both my personal mac with no VPN, and my work mac (with a VPN) stopped working at the same time months ago:

> We were unable to load KBFS (Fuse kext). This may be due to a limitation in MacOS where there aren't any device slots available. Device slots can be taken up by apps such as VMWare, VirtualBox, anti-virus programs, VPN programs and Intel HAXM.
> Please run `keybase log send` to report the error.

my log id: e99460a9848ba19f60795b1c

Start with the reported Catalina KBFS/Fuse kext error and the supplied log ID e99460a9848ba19f60795b1c; review the output from `keybase log send` and compare the behavior on the two Macs. Done means identifying a reproducible cause for KBFS failing to load or documenting the missing diagnostic needed to proceed.

Written by the indexing model from the issue text.