Thank you Techman. I resolved this problem by disconnecting the lock from the Ultraloq wifi bridge and then including it again even though the IoX node was still listed. I included as a new node and I was then able to 'Remove Fail Node' on the old node. I think that using the Ultraloq wifi bridge as well as Zwave was creating problems.
Not too many posts on this forum regarding Ultraloq U-bolt locks, so I'll add some info here in case someone else comes up with issues. I like these locks quite a bit although I don't have anything to compare them with. They seem to be solidly built. I wouldn't spend money on the fingerprint feature because it just doesn't work reliably. I was having some quirky behaviors with my 2 locks, so I disconnected both of them from their wifi bridge (each bridge only accommodates a single lock) and only use the UD Mobile app for remote status and activation and zwave inclusion/exclusion. I still can get full lock status with the Ultraloq app using bluetooth; gives me all the other features like access logs, firmware version, etc. Battery life may be an issue; some users report only 4-8 weeks of life using rechargeable NiMH.