2 days ago I said the DID doesn't leak but I take it back, even with the screw on the fill hole it can still leak (through the wick I guess). It just happened to me today, it was upside down for like 10-20 minutes and I noticed after that around 2ml has leak out of it !
It's not a good idea to put the DID upside down... maybe if I fold the edge at the top of the wick or just pinch the top it will help not to leak as much though...
All gens will leak if not kept upright. Pinching wick and using screw in fill hole changes the vape and the flavor. IMO dont pinch the wick nor use the fill hole screw. All my gens stay at home for vaping.
say it's your top connection is not solidly secured. Just a guess.