Impossible. All factors being equal, your still simply cannot stop condensing. Even if there were no cooling water whatsoever, you would still get some latent heat loss somewhere and get vapor condensation ,if, albeit very little,. The only way this would happen is if your still was under full reflux before the condenser. If you are using a Brewhaus still, this would come from the cooling lines in the stillhead. Of course, you would need a pretty amazing flow of ultra-cold water to maintain that for any length of time, and I still think you would have had some slip by and make it to the condenser.

My first guess would be that your heating failed, and didn't ,for whatever reason, provide enough heat to boil whatever was in your boiler. It might SOUND like it's boiling in this case, but it would not be.

My second guess would be that your packing was too tight and it was choking. This can take awhile to notice, but again you would have still condensed SOMETHING ,unless you didn't wait long enough,.

My third guess would be vapor loss somewhere in the system. This can be difficult to spot, will cripple your run, and is very dangerous to boot. It is possible that you developed a leak somewhere and that, during your process of disassembling the condenser and rebuilding, you resolved this problem. I'd keep an eye on it now, just to be sure. Actually, I'd probably do a run of water at the highest heat I could manage, and spread soapy water over the still and check for leaks. ANY possibility of leakage must be addressed with the utmost concern.

I just had a sililar output problem. I woke up and temp slipped to 62, maybe half a pint after ten hours. I reset the still on heat source and temp shot up. I thought all was fine, went to work and when I came home temp said 75 which is right for my house. However only about a quart. I ordered a new heat source from here. I know you hear it boiling, but my heat source just didn't have the output anymore to get the ethanol up the tube.