Unknown Contacts Locking Records

H,i opened an SR but was told to post in CCC,

Main Question: Is it possible to unlock a record from another contact that dosent exist in the system anymore?

We are occasionally getting errors in our integration to CX Sales when trying to update records using SOAP merge method. Error message is 'Another user hold the lock [CUID]...'.

However, when searching for this contact we are unable find the user. We have also tried searching in CDM with inative records and via API, but no luck.

Full error message below:

Is there a method to unlock records in Sales, best practice to prevent locking in OIC, or a process to run to wipe possible old contacts locking records?