Script works in powershell and command line but fails from SQLAgent job step

GlynLamb I have been working through a somewhat similar problem.  To debug it, I setup a test version of the script that uses a different (new) output table using  Write-DbaDbTableData -AutoCreateTable, then compare the resulting new table schema to what is expected.  That helped me.  But as to differences in Powershell behavior between command line vs SQLAgent, my only experience is that I can't use the "Powershell" jobstep defined by SQLAgent, rather must use "Operating System (CmdExec)" to control the Powershell version in use.  Which you are probably already doing.