AGS Exports from OpenGround / Holebase SI- unseen characters causing failure of AGS Validator Check

We've received an AGS from a contractor that looks to have been exported from either HolebaseSI or OpenGround.

When run through the AGS Validator it is returning:

FAIL: AGS Format Rule 3:

Line 1 Does not start with a valid data descriptor.

FAIL: AGS Format Rule 3:

Line 1 Contains fields that are not enclosed in double quotes

When viewing the file in Notepad++ there does not appear to be any obvious issue, even when showing non-ascii characters (which, as an aside, also seem to be picking up hyphens as problematic)

However, viewing it in HEX reveals that there are additional characters before the first heading in Line 1

Once these additional characters are removed then the two Fail messages are not present when the validator is run.

Can you please advise as to why this may be occurring and whether a fix will be put in place?