I also think the DEV's forgot to deploy a compatible sentinel. Already tried a 'dirty hack' using a foreign version of sentinel with arcticcoin - but it was not compatible at all.

Btw. does anyone still have contact to the dev's? Tried by PM, Twitter, E-Mail. NO RESPONSE. I sadly still think this behaving only can indicate the coin has become dead at all or the DEV's are just arrogant.