read_metadata errors with "adding class "factor" to invalid object"

[combiz]

  ── Reading sample metadata ─────────────────────────────────────────────────────
  ✔ Five metadata variables loaded for manifest='sivus'
  Error in attributes(xx) <- attributes(x) : 
    adding class "factor" to an invalid object
  Calls: read_metadata ... .transformer -> inline_collapse -> %||% -> inline_generic
  Execution halted