I have never had that exact issue before but I have had, on various airlines, various BPs with my name in different formats. My name in my passport is correctly in the format: FIRSTNAME DOUBLE-BARREL (including hyphen), and I've had BPs which say:
FIRSTNAME DOUBLEBARREL (most common)
FIRSTNAME DOUBLE BARREL
BARREL DOUBLE FIRSTNAME
FIRSTNAME BARREL
and in fact all sorts of weird combinations. It seems Finnair were being rather officious.
I've never had a BP or ticket which includes the hyphen in my name.
I note you're a Dubliner. You don't by any chance have an Irish name with a non-standard Roman letter, like Máirtín? I wonder if the presence of such a character might throw the system.