This is likely an old style JPEG in TIFF which is not supported in ImgX. This style of TIFF is considered broken and LibTiff (a standard for TIFF reading and writing) will not read this format.
Sorry for bumping this, but I couldn't find any more info on old jpeg elsewhere.
We got an MFP that scans document to old jpeg tiffs, and these shows fine with the ImgX6.4.
We do have files that show that exactly same error message, so if it's not old jpeg issue, then why are
those files regarded as invalid?