The XMP metadata is part of the TIFF file and it sounds like either it contains something that is causing a PDF/G error or the XMP is corrupted. Without the file it will be difficult to determine, also what version of LC are you using?
What version is your LiveCycle at? I was able to convert your TIFF to PDF (13 seconds) using ES 4 PDFG (184.108.40.206).
There may have been some bug in the version you have, which appears corrected now.
Thanks for response.
Version: 11.0.0, GM
Service Pack Version: N/A
Patch Version: N/A
I see no newer version on Adobe Licensing website
Interesting. It converted fine for me with the collateral you shared.