Is there some newer problem about decimal units and "My Snipe Target"?

The German ebay.de does require entry with decimal comma. An entry with decimal dots is refused.

myibay does require decimal entries with decimal dots.

I just observed a bid, reporting:
My Status: Your snipe was too low due to eBay's bid increment system

... at a final value of US $0.26 and a snipe of
US $0.66

The bid amount on ebay.com would have to exceed 0.31 for that amount. On ebay.de these would be usual steps in 1.00 (€).

My Snipe Target ist set to Auto - which should be that bids are done on the US ebay.com, but if not possible on UK ebay.co.uk. This should work with the same decimal dot.

What's the reason why it did fail? Did it try to bid on ebay.de, without changing from decimal dot to decimal comma?

Please always provide the item number so I can check exactly what happened.
It's possible there was a late bid retraction so your bid was not accepted. But I can't say for sure without any relevant information such as item number.