Error while parsing header with 64-bit file size

[xofyarg]

Hi, I'm trying to identify an error, which throws the following msg:

Invalid GNU filename index field in entry header ("SYM64/         ")

It seems like a file size notation from wikipedia:

To overcome the 4 GiB file size limit some operating system like Solaris 11.2 and GNU use a variant lookup table. Instead of 32-bit integers, 64-bit integers are used in the symbol lookup tables. The string "/SYM64/" instead "/" is used as identifier for this table[14]

I'm not sure how to generate such an archive file, but GNU ar 2.38 seems has no problem listing the file names and their sizes. Here's the header in hex which is causing the issue:

[2f, 53, 59, 4d, 36, 34, 2f, 20, 20, 20, 20, 20, 20, 20, 20, 20, 30, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 30, 20, 20, 20, 20, 20, 30, 20, 20, 20, 20, 20, 30, 20, 20, 20, 20, 20, 20, 20, 34, 33, 33, 36, 34, 30, 38, 20, 20, 20, 60, 0a]

Please let me know if you need more info, thanks.