Hi Morgan,
I'm using the same version (2.5.5-0-g9fecd73) With Linux (Debian
Wheezy), and I'm having the same problem. Sometimes it snipes, and
sometimes not. In all cases, the snipes were well above the winning
bid, and by more than the correct bidding increment for that
amount.
Also it sometimes (very occasionally) marks auctions as 'ended' and
moves them to complete well before they are over.
I'm sniping from eBay.com.au, and from my settings the snipes
are being placed on eBay.co.uk (I haven't tried changing that to
eBay.com).
I've temporarily gone back to version 2.5.3pre3-2-g03a9bc3
(incorrect shipping values, incorrect fixed price, etc... and all)
as that version still seems to snipe OK.
I hope this helps to find the problem, and thanks for an
excellent and full-featured sniping program.