Update - I have created Temp Jobs to keep backups going on critical VMs, but still working on resolving the Tag Issue. Like I stated before, my backup jobs and backup copy jobs are based upon tags. I was trying to work around having to do another Full Backup (space reasons) of everything.
Veeam Support - I worked with support and did some troubleshooting with the certificates and using different vCenter credentials to connect with. I was recommended to open a case with VMware because of the error "failed to initialize Inventory Service" message. It is what vCenter is kicking back to Veeam, so they wanted me to check with VMware and have them look into my vCenter logs.
VMware Support - That is still where I am at today. They reviewed my support bundle and there was no clear evidence of what the issue is. The inventory service is running and performing inside VMware with no issue as well. Support has logged in and restarted services and tried to capture logs as the jobs ran and so forth. This has been going on for a couple weeks (Holidays have played a part in this long time frame). Tonight I created a snapshot and deleted ALL tags and categories. That did not fix the issue, but then I went through this KB "How to reset Inventory Service database for vCenter Server Appliance 6.0 (2146248)" on the VMware site (recommended to do by VMware). That completed successfully, but the issue still remained in both Veeam 9.0 (production) and Veeam 9.5 (test production vm) servers. After rebooting the VMs (to verify a reboot wouldn't fix anything) I reverted back to the snapshot and back where I left off.
I have probably skipped out on a number of other attempts that were made to resolve this issue. The condition remains the same...