Ok, so apparently it just wanted me to create this topic in order to start working. 😉
I had previously come across this link: https://forums.openvpn.net/viewtopic.php?t=33561 where the person had to go to http(s)://pfsense.router.ip.address/status_filter_reload.php to get things working again. Well I had tried that at the very beginning, but not again since reconfiguring the server settings on the one upgraded to pfSense 2.6.0. After writing the opening for the thread, I went back over my steps, and figured it couldn't hurt to run the filter reload again, even though I had been applying changes to the firewall filters during troubleshooting. As soon as I reloaded the filter, I began receiving pings from a LAN address on the internal network through OpenVPN that was a separate address from the pfSense box. The only other thing I additionally did was to add outbound NAT rules, specifically for my OpenVPN ranges to LAN, although automatic created the same rule plus more. I suspect this was the answer as typically you need some sort of a NAT to route through a firewall. However, there wasn't one setup in the previous config (pfSense 2.4.5-RELEASE-p1), so... 🤷 Hopefully writing up this response will help someone (possibly even myself in the future) if they experience the same problem.