Accidental DBA: Unsure why I have a broken log chain?
Your command for full backup 


  --Take full backup to begin new TLogChain
  
  backup database DbNameHereCorrupt to disk = @fullBackupPath with init, differential;


does not make full backup.


  DIFFERENTIAL
  
  Used only with BACKUP DATABASE, specifies that the database or file
  backup should consist only of the portions of the database or file
  changed since the last full backup.


As @dbamex mentioned full and restore commands use different file names.