Exception: Unable to cast object of type 'System.String'

[IsaacM72]

Good morning!
I started testing this solution as I'm just not getting my own scripts working correctly. So far it has worked really well on reducing versions of existing files on SP. We did not bring the original default down from 500 during the initial migration so have to manually clean up the historic data.
On to the Question: I get the error below on random files, obviously the ones that I really need get rid of 200 plus versions. I left the file name in part as it is quite long and it has an ampersand in it (&) although I have the same in some other files not creating the error.
All I get from the MS support info is that the column format is incorrect, but there are multiple files that are not affected in the same column.

[2025/11/14 06:28:58] , [Error] , [0] , [RemoveFileVersionAuto] , "Error processing Item '/sites/XXX/Shared Documents/MXXX/Do not use_Brand plans XX & XXX 2026.pptx'"
[2025/11/14 06:28:58] , [Error] , [0] , [RemoveFileVersionAuto] , "Exception: Unable to cast object of type 'System.String' to type 'Microsoft.SharePoint.Client.FieldLookupValue'."
[2025/11/14 06:28:58] , [Error] , [0] , [RemoveFileVersionAuto] , "Trace: at NovaPointLibrary.Solutions.Automation.RemoveFileVersionAutoRecord.AddFileDetails(ListItem oItem, String versionsDeletedCount, String versionsDeletedMB)
at NovaPointLibrary.Solutions.Automation.RemoveFileVersionAuto.RemoveFileVersions(SPOTenantItemRecord resultItem)
at NovaPointLibrary.Solutions.Automation.RemoveFileVersionAuto.RunScriptAsync()"