At this point it seems like the fact that I am not using user/pw auth for OpenVPN seems to be the big differ here. The working config which is to an OPNSense gateway has a username/pw for it and the non-working config to the Ubuntu gateway just uses the certificate authentication.
Looks like the slate is running 2.4.5
OPNSense is running 2.4.8
Ubuntu Linux is running 2.4.4